Add devise and user model

@SeattleDIY/owners 

This adds the following features (a few should have been their own branch, sorry about that):

* Configures the application to be able to run under Pow http://pow.cx
* Fixes a configuration issue with rspec + zeus that I ran into
* Removes turbolinks from Rails, we don't need that shit
* Adds Devise
* Configures a default mailer host
* Copied all the Devise views into `app/views` for easier modification as needed
* Created User model
* Enabled confirmable on the User model

Especially take note of the options I chose for Devise. If we don't need/want email confirmation, for example, I can easily turn it off and update this pull request.