Create an import command that is able to import warps from a warps.txt file (file generated from Bukkit's predecessor, Hey0).

The warps are newline delimited and an example was posted by AlsoKnownAsJazz here:
http://forums.bukkit.org/threads/tp-niftywarp-v1-2-warp-home-plugin-based-on-privacy-visibility-of-warps-1000.23339/page-2#post-513480

The import command should have a way of specifying an import handler/routine to use. This is to allow for importing from multiple formats.

For instance, the default importer should be an importer that will read in warps created from the exporter defined in Issue #22. This warps.txt importer would be an alternate import implementation.