Removed BattlePluginsAPI

People have been reporting this impossible error as a BattleArena bug.

Yes, it was impossible for BattleArena to produce this error.

Finally, someone produced a FULL server.log including the error and I was
able to trace it to BattleTracker.

Finally fixed. Another one bite the dust!

Good job team!
BattleTracker v2.5.8.10

Removed BattlePluginsAPI

formatted Tracker.java

pom.xml:
- added repo
- added ant copy-file
- removed mc.battleplugins dependency