Make game collection use promises. Delete some README files. Add a game model.

Rename GameCollection to OwnedGameCollection to distinguish between different endpoints in the
bgg api. Give it a method called fetchWithRetries that returns a $ promise which resolves when the
collection finally gets data instead of a "still processing" response.

Also: delete some README placeholders. Add a GameModel that doesn't do anything yet. Add some
diagnostic behavior to the index which will be changed later.
Add DetailedGameCollection

Add new collection which contains an OwnedGameCollection and will soon be responsible for
making batched requests for details for the owned games.