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). 

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*Edited by turt2live*

**Related Links:**
- Glowkit: GlowstoneMC/Glowkit#31
- Ticket: #139 
Can't I just leave this as a stub to note that these fields are required a la Vanilla NBT data that I've been able to gather?