Adding Teams#show action.
Adding new and create actions to Teams.
Adding security checks and tests for Teams#new.
Adding Teams#destroy action with tests.
Merge pull request #2 from PaulDib/adding_team_actions

Adding team show, new, create and destroy action.
Removing signed_in_player? from TeamsController.
Preventing signed in users from signing up again.
Removing the warning on mass assignment.
Merge pull request #6 from PaulDib/signedin_players_cannot_create_new_players

Preventing signed in users from signing up again.
Merging development into feature/news