Initial update for 1.7.8

CB managed to patch up to 1.7.8, even though 1.7.9 is a possibility in
the near future... still, Denizen always stays on top of CB updates, and
this one shall be no different!
First part of UUID support, p@uuid

dPlayer objects now use the UUID to identify, so they can remain valid
even if a player renames.
As a side effect of the renaming system, we can't store player objects
like we used to, and have to go back to gathering player lists from
Bukkit functions and the like.
NEXT UP: Changing the saves.yml file to only use UUIDs...
Catch a few errors

- Showfake command debugging wrong and potentially throwing NPEs
- NPCDespawnEvent can fire for already-unspawned NPCs apparently, don't
try to stop the despawn if they're in a chunkload area.
Merge pull request #746 from mcmonkey4eva/master

Pull request for CB updates