Make a better way to battle AIs against each other

[timpalpant]

There is a battle driver that will play AIs against each other by creating computer clients and connecting them to a game server (https://github.com/timpalpant/rummy/blob/master/clients/ai/battle/main.go). This is overly complex and slow; a system for playing AIs against each other could be developed by just making a new Game (https://github.com/timpalpant/rummy/blob/master/game.go#L46) and then having the AIs call methods on it.