[03:49:44] [Server thread/ERROR]: Could not load 'plugins/Vault.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.IllegalStateException: JavaPlugin requires org.bukkit.plugin.java.PluginClassLoader
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:147) ~[JavaPluginLoader.class:git-Cauldron-MCPC-Plus-1.7.10-1.1199.01.162]
at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[SimplePluginManager.class:git-Cauldron-MCPC-Plus-1.7.10-1.1199.01.162]
at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) [SimplePluginManager.class:git-Cauldron-MCPC-Plus-1.7.10-1.1199.01.162]
at org.bukkit.craftbukkit.v1_7_R4.CraftServer.loadPlugins(CraftServer.java:318) [CraftServer.class:git-Cauldron-MCPC-Plus-1.7.10-1.1199.01.162]
at net.minecraft.world.storage.SaveHandler.initBukkitData(SaveHandler.java:458) [ayq.class:?]
at net.minecraft.world.storage.SaveHandler.func_75757_d(SaveHandler.java:136) [ayq.class:?]
at net.minecraft.world.World.(World.java:352) [ahb.class:?]
at net.minecraft.world.WorldServer.(WorldServer.java:153) [mt.class:?]
at net.minecraft.server.MinecraftServer.func_71247_a(MinecraftServer.java:356) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:328) [lt.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:624) [MinecraftServer.class:?]
at java.lang.Thread.run(Thread.java:745) [?:1.7.0_60]
Caused by: java.lang.IllegalStateException: JavaPlugin requires org.bukkit.plugin.java.PluginClassLoader
at org.bukkit.plugin.java.JavaPlugin.(JavaPlugin.java:64) ~[JavaPlugin.class:git-Cauldron-MCPC-Plus-1.7.10-1.1199.01.162]
at net.milkbowl.vault.Vault.(Vault.java:114) ~[Vault.class:?]
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.7.0_60]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) ~[?:1.7.0_60]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.7.0_60]
at java.lang.reflect.Constructor.newInstance(Constructor.java:526) ~[?:1.7.0_60]
at java.lang.Class.newInstance(Class.java:374) ~[?:1.7.0_60]
at org.bukkit.plugin.java.PluginClassLoader.(PluginClassLoader.java:201) ~[PluginClassLoader.class:git-Cauldron-MCPC-Plus-1.7.10-1.1199.01.162]
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:143) ~[JavaPluginLoader.class:git-Cauldron-MCPC-Plus-1.7.10-1.1199.01.162]
... 11 more

Not a Vault issue, Cauldron should fix it's classloader.