Automated the need to update Bukkit import paths

Maven saves the day again! No more messing with changing the MC and
bukkit import path for version changes. , Ex: net.minecraft.*.v1_5_R2 =>
net.mincraft.*.v1_5_R3, just set the POM properties for old version and
current version, the plug-in will replace everything for you :D
Renamed the `current` auto-replace prop. to `new`

...for the sake of clarity + a comment!