Add the activate account step to the verified workflow.

* Changing approach such that email activation is not a step.
* Removing stale line of code.

@wedaly @dianakhuang @rlucioni 
I have a slight preference to include this line in `_requirements()` and pass in `user.is_active` as an argument, just so we're configuring the requirements dict in one place.  This is a nitpick, though.