Hello! I found some problems in automatically installing a modpack by MC Instance Loader. Many mods were unable to be downloaded if the certification of the download site is invalid. Can you add a configuration option to be able to trust all the sites to avoid this problem? Thank you very much! Errors in the log are like this:

[02:10:12] [Server thread/INFO] [MCInstance Loader/mcinstanceloader]: Downloading HardcoreEnderExpansion... (632/743 resources)
[02:10:12] [Server thread/INFO] [MCInstance Loader/mcinstanceloader]: An error occured while downloading the file, trying again...
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.Alert.createSSLException(Alert.java:131)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.TransportContext.fatal(TransportContext.java:324)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.TransportContext.fatal(TransportContext.java:267)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.TransportContext.fatal(TransportContext.java:262)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:654)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.CertificateMessage$T12CertificateConsumer.onCertificate(CertificateMessage.java:473)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.CertificateMessage$T12CertificateConsumer.consume(CertificateMessage.java:369)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:377)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:444)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:422)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.TransportContext.dispatch(TransportContext.java:182)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.SSLTransport.decode(SSLTransport.java:152)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1392)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1300)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:435)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:559)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:197)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1570)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.net.www.protocol.http.HttpURLConnection.access$200(HttpURLConnection.java:92)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.net.www.protocol.http.HttpURLConnection$9.run(HttpURLConnection.java:1490)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.net.www.protocol.http.HttpURLConnection$9.run(HttpURLConnection.java:1488)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at java.security.AccessController.doPrivileged(Native Method)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at java.security.AccessController.doPrivilegedWithCombiner(AccessController.java:784)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1487)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:352)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.hrudyplayz.mcinstanceloader.utils.WebHelper.downloadFile(WebHelper.java:59)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.hrudyplayz.mcinstanceloader.utils.WebHelper.downloadFile(WebHelper.java:77)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.hrudyplayz.mcinstanceloader.utils.WebHelper.downloadFile(WebHelper.java:34)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.hrudyplayz.mcinstanceloader.resources.ResourceObject.downloadFile(ResourceObject.java:467)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.hrudyplayz.mcinstanceloader.Main.downloadResources(Main.java:443)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.hrudyplayz.mcinstanceloader.Main.secondPhase(Main.java:69)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.hrudyplayz.mcinstanceloader.ForgeMod.preInit(ForgeMod.java:27)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at java.lang.reflect.Method.invoke(Method.java:498)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:532)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at java.lang.reflect.Method.invoke(Method.java:498)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.EventBus.post(EventBus.java:275)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at cpw.mods.fml.common.LoadController.sendEventToModContainer(LoadController.java:212)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:190)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at java.lang.reflect.Method.invoke(Method.java:498)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at com.google.common.eventbus.EventBus.post(EventBus.java:275)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:119)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at cpw.mods.fml.common.Loader.preinitializeMods(Loader.java:556)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at cpw.mods.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:88)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at cpw.mods.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:314)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:117)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:387)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:456)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:323)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.validator.Validator.validate(Validator.java:271)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:315)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:223)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:129)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:638)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: ... 60 more
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:451)
[02:10:13] [Server thread/INFO] [STDERR/mcinstanceloader]: [java.lang.Throwable$WrappedPrintStream:println:749]: ... 66 more
[02:10:13] [Server thread/ERROR] [MCInstance Loader/mcinstanceloader]: Error while downloading HardcoreEnderExpansion. (There was an issue writing to file.)
[02:10:13] [Server thread/INFO] [MCInstance Loader/mcinstanceloader]: Failed to install the mcinstance file!
[02:10:13] [Server thread/DEBUG] [FML/mcinstanceloader]: Bar Step: MCInstance: Downloading resource - HardcoreEnderExpansion took 1.382s

Will work on it in v3.0, it's probably gonna be as a config to ignore HTTPS certificates. Didn't even know HTTPUrlConnection fully handled certificates xD

Seems to be fixed in 2.7, don't hesitate to recreate the issue if it still happens.
The fix involves enabling the certificate bypass in the config.