Issue 1778 - Automated Test - new user signup

Adds a user_create feature to test success and failure cases of new user registration.

Tests for this functionality existed in features/others/invite_queue before, but there were only two scenarios, there was a lot of repetition, and it was only making assertions based on the UI (rather than checking to see if a new user had been created in the DB). I moved the tests into their own file (since they don't actually test or rely on the invite queue) and broke them up a bit more.

https://code.google.com/p/otwarchive/issues/detail?id=1778