[In Progress] Spigot-CraftBukkit 1.8 compatibility. Implements #442

This branch holds the visible progress on a 1.8-compatible EchoPet release. Anything here should **only** be used for testing purposes (which will be conducted once this branch is closer to completion. This pull request also implements issue #442.

The following list will be updated as progress is made.

Currently completed:
- [x] General module update, as per usual (NMS updates, mostly for the obfuscation changes from v1_7_R4 -> v1_8_R1).
- [x] Updating of dependencies ([PowerMessage has been updated to support the few changes in protocol handling](https://github.com/DSH105/PowerMessage/commit/3c18d185d06cfd0e717e055c06a50f699f5f4861)).
- [ ] Entity datawatchers are still mapped to the 1.7 values; this needs to be updated to support 1.8 clients (causes client crashes).
- [ ] Plugin testing (at this stage, entity registration seems to be causing problems with pet spawning).

Once I am satisfied with the stability of the 1.8 module, it will be merged into the master branch and published to BukkitDev.