Add game management

[barrybecker4]

We want to have support for multiple concurrent multiplayer games.
There will need to be a "game" table for storing the open and current games.
Users will be able to create games in a "open games" view.
These are the fields for a game:

• number of players. When the requisite number of players is reached, the game automatically starts.
• the region where the game will take place. Initially this may be hard-coded, but we should eventually allow the creator to specify the geographic region by dragging out a rectangle.
• The ids of the players in the game.
• The duration of the game in hours. This will be a number between 1 and 10,000.
• Timestamp for when the game starts and stops. It may stop before the limit if players resign.
• The creator of the game.

Some other notes:

• A player can only belong to one active game at a time. To join a different game they must first withdraw/resign from others.
• A player can only create one game at a time. To create another, they must first delete any earlier game that was create, or wait for it to finish.
• A game cannot be destroyed if there are players who have joined it (even if it has not started).

[barrybecker4]

Regions and users need to belong to a game.