login_as only accepts a fixture symbol

I tend to favor factories and datasets over fixtures, but getting rid of the user fixtures generally means a lot of work in the boilerplate restful_auth tests.

As one step in the right direction, I made a small tweak to login_as. If you pass a user model (or whatever model you chose to authenticate) it will use that instead of looking for a fixture. I've attached the git diff patch to this ticket.

This makes divorcing fixtures in restful_auth possible. I've also thought about making it downright pleasant by modifying the TestUnit functional tests to be more fixture-agnostic. My first thought is to limit the fixture calls (ie, users(:quentin) down to just once in the setup method. That way, a developer could change:

def setup @user = users(:quentin) end

to:

def setup @user = Factory.create(:user) end

at the top of tests and most, if not all, of the change is done. Feedback on this idea would be appreciated.