Check if player has a mcMMOPlayer object

Fixes #1976
Fix bug where dodge would check the wrong player
Fix the calculations for Iron Arm Style in the Unarmed command.
Added API to XP events to get XP gain reason
Use strings instead of OfflinePlayers for scoreboards.

(cherry picked from commit 89b596591ec1974e0201395dc6e76353e4709572)
Fix formatting

(cherry picked from commit 4e36073e6e2dc3aeba087d605cef79fc4a8a9779)
Make sure to shorten long ability and skill names

(cherry picked from commit 236ccd6ebdd0834f87b373794e1597ef36fb2ff6)
Fix /party teleport command

Why did we use getCommand("ptp").getExecutor() again?

Fixes #1995
Update README.md
Prepare for UUID update
Add u.uuid here