Finish match invitation system. Closes #26, finally
Implemented basics of plugin metrics. Closes #77

http://mcstats.org/plugin/AutoReferee
Fix player beds when joining team. Remove name coloring code
Fix bug with enderman block pickup on worlds where mob spawn is restricted

SPECULATION: Minecraft seems to allow endermen to pickup/interact with
blocks at some strange time right as they spawn. This means that if an
enderman spawns, attempts to immediately pickup a block, and then the
spawn is cancelled, the EntityBlockChangeEvent won't have an entity to
refer to in its callback handler.

The block, however, is guaranteed to exist, so just changing the code to
get the World from the block, not the entity.
More work on the command management framework

Insufficient permissions/roles are reported back to the command sender,
so that they know why the command failed. The message should tell them
what role they have if the failure was because of their role (spectator,
player, etc).