Level logic into TankLevel; map is now in TankLevelMap

Can't play because there are no player tanks in level. Will need fix client side.
Will be in next commit.

Change-Id: I044ba372d164a4b1e759bd4f9a8f7883052b2d4d
UI to display different game states

Change-Id: Ib8d23cf95a744b7e995bb2061d820f5b9fd04e59