Bracket

Progress in tournament functionality: bracket and group stage pairing
- Models for Tournament, TournPair, TournUser, TournDeck
- instance methods in Tournament: initiate_bracket, initiate_groups(int)
       *tests for these methods in tournament spec
- basic views for testing tournament creation and bracket viewing
Unused method argument - `pod_number`. If it's necessary, use `_` or `_pod_number` as an argument name to indicate that it won't be used. You can also write as `get_num_users_in_pod(*)` if you want the method to accept any arguments but don't care about them.