[refs #2] fixed existant -> existent
[refs #2] moved skipped authenticated tests to integration
[refs #2] covered omniauth callbacks controller in integration
[refs #2] added invite mailer, added coveralls
[refs #2] moved to minitest + capybara
[refs #2] added invite and leave features
[refs #2] added form for team edit
[refs #2] added button to add new team, fixed duplication of mates