Mailing

Card: https://trello.com/c/zp8ibqBS/11-email-notifications-no-configuration-initially-send-an-email-notification-to-everyone-whenever-a-board-is-created-a-card-is-crea
Also. One could test that his application is behaving correctly sending the email, but we actually didn't add any logic to mail sending (e.g. It is a straightforward call to the rails library) and thus it does not deserve any regression test because it wouldn't catch anything useful.