def invalidate!
      self.active = false
      self.save!
      if controller
        cookies.delete(:user_session)
      end
      Authie.config.events.dispatch(:session_invalidated, self)
      true
    end
def invalidate!
      self.active = false
      self.save!
      if controller
        cookies.delete(:user_session)
      end
      Authie.config.events.dispatch(:session_invalidated, self)
      true
    end
Mark this session as invalid