Add the abstract Game class.
Add number of players.
Delete ChatRoom
Make the game defs an input parameter of GameRoom.

Update TicTacToe and ConnectFour to match the new definitions.
Refactor the model part of the GameType.

- Make creating a game independent of the Actor model.
- GameType has a ``model`` parameter instead of a ``props`` parameter.
- ``model`` is passed in as a parameter to GameRoom.
Get rid of extraneous Room subclasses.
Fix spectators error.