Added license information and Maven plugin to auto-generate the license header in every Java file.
Removed unnecessary class in preparation of a major rewrite to the small amount of existing selection code.
Made InstanceGame implement 'Game'.
Made both SingleInstanceGame and MultiInstanceGame abstract classes rather than interfaces.
Rewrote some of the existing arena library code.  Now following a similar structure as Games.  ArenaHandler -> SingleArenaHandler/MultiArenaHandler