adds `check_for_valid_user` :before_hook

When a user registers for the system via Twitter, there is a
period of time when the user is a registered, active user, but
doesn't have complete information. In this case, if they try
to get around the app, previously it would let them. Now we
catch them and redirect them to a signup page to complete their
basic registration information.
sends incomplete registration to signup instead of dashboard on twitter login