Added mcpc.yml config which will store all MCPC+ specific settings.

The new config will be located in root of your server directory. There
will now be 3 total configs : bukkit.yml, mcpc.yml, and spigot.yml. Each
config file will hold their respective settings.

* Created new CraftCustomContainer class which will be the default
BlockState class used by modded inventory containers. This fixes
InventoryHolder bug when trying to access Locations from plugins.
It will also fix insert-item and insert-remove logging with MCPC+ Prism builds.

* Removed item banning code. If you wish to ban specific items and/or recipes,
try using ModifyWorld and Recipear.

* Cleaned up some code.