Add bare bone implementations for some Entities

So, I started out to implement all known Entity interfaces from Bukkit API (and some from Minecraft), but as of late, I do not have the time to produce said implementations with all the proper storages, hooks and missing APIs.

I'm opening this PR in hopes that someone may pick up where I left off. This PR is dependent on https://github.com/gabizou/Bukkit/tree/glowstone-entity-1.8-update for some of the 1.8 entities (Guardian, Rabbit, and Endermite). 
Instead of packaging, an interface would likely be more ideal. No need for 3200 imports when said interface is already accessible.