Convenience Methods for Minecraft Protocol and distinction in CreatureType

This PR adds some convenience methods for CreatureType adding Protocol Names and allowing the CreatureType to be gotten from the Entity.

https://github.com/somners/Vanilla/blob/87a4fe35a224c2b74a0491706ace68c6a638873f/src/main/java/org/spout/vanilla/plugin/protocol/entity/creature/CreatureType.java