[WIP] Test authentication

### Work in Progress

@cored, @sampritipanda, and I have been stirring this around on various branches for a while.

This is rough draft of a proposal for the [authentication controller's](https://github.com/johnnymo87/WebsiteOne/blob/test-authentication/app/controllers/authentications_controller.rb) `create` method. It uses [spec/requests/authentications_spec.rb](https://github.com/johnnymo87/WebsiteOne/blob/test-authentication/spec/requests/authentications_spec.rb) as a guide.
I was doing a working interview today, and I found a gem for this very kind of thing! https://github.com/Originate/response_state