Completely restructured the internals of the plugin

This is something that has been needed for a while, and will make way
for future features. Most importantly, this patch originated around
the future implementation of player UUIDs.

This patch implements two key features:
  - Support for Bukkit's event system with VindicatorEvents
  - Significantly cleaner implementations using Vindicator
pom: migrated groupId to org.jgeboski
Storage: expanded the Storage interface

These additions will be used with features added in the future as well
as allowing other plugins access to a more feature rich storage engine.