Implement match log. Add feature tests.

Create serialized match_log, write to it from controller, and add it to the match results email.

Create tests that check match_log basic functionality and inclusion in match results email.

Create feature test for league creation, drafting, and matches. Add in_browser helper to spec_helper. Build out more of the league fabricator. Clarify match_log events from match_controller.
Wrap draft.choose in a check: token.team == nil

This should prevent the problem of a user requesting to choose a player twice, and thus incrementing the current position of the draft twice, even though they only get one player.
Display other team's recent picks on draft page.
Merge branch 'match_log'