Create simple lobby system and games that track status.

* Create simple lobby that displays games and their status.
* Allow users to create a new game.
* Allow users to join a game.
* Allow users to end/close a game.

Currently game links are pretty wide open and mapped directly to their firebase ids. Both these things are probably not ideal - later when we have actual users we may consider using the user id to track users within game.

See [live deployment here](https://storieswithfriends.firebaseapp.com/#/lobby).