Added tests to the team controller
Added tests to validate invite model
Added tests to validate invites controller
Updated users_to_invite method so it doesn't include users that already have a team.
NOTE: users can belong to one team only
Fixed migrations problem
Real fix for the migration issue
Merge pull request #25 from mitadmin/games_creation

Fix migration problem and updated team invites management
broke down teams view so it is not so big and fixed layout problem with flash messages
merged upstream and resolved conflicts