Fix error in authentication + changing passphrase

The problem flow was:
  Visit Client app (e.g. publisher).
  Redirected to signon
  Login to signon
  Password change required
  Change password
  Error message saying "The authoprization server does not support this response type."

The underlying cause was that devise_security_extension was returning you to
the request.path, which excluded the querystring, which the OAuth flow needed.
The fix was to change the gem to return you to the fullpath.
Merge pull request #78 from alphagov/fix_oauth_error_passphrase_expired

Fix error in authentication + changing passphrase