* DEV: Replace User.unstage and User#unstage API with User#unstage!
Quoting @SamSaffron:
> User.unstage mixes concerns of both unstaging users and updating params which is fragile/surprising.
> u.unstage destroys notifications and raises a user_unstaged event prior to the user becoming unstaged and the user object being saved.
User#unstage! no longer updates user attributes and saves the object before triggering the `user_unstaged` event.
* Update one more spec
* Assign attributes after unstaging