Now includes role name reset, multiple words, error detection.

Update AFKHandler.java

See merge request !1

Teams previously got lost during a server restart if the only
member left was afk and not in his real team. Also changed
the map to use UUID to make it easier to serialize.

This bug was because a reload restarts the plugin hence data cannot be
stored over a reload. Therefore the afk status was not properly recognized
and the player had was in the afk team without the plugin recognizing.