def create
      authorize! :moderate, @group
      if @group.active_memberships.empty?
        redirect_to root_path, alert: "Could not log in as moderator "\
        "because there are no active memberships for this group."
      else
        sign_in @group.moderating_participant
        redirect_to social_networking.social_networking_profile_path
      end
    end
def create
      authorize! :moderate, @group
      if @group.active_memberships.empty?
        redirect_to root_path, alert: "Could not log in as moderator "\
        "because there are no active memberships for this group."
      else
        sign_in @group.moderating_participant
        redirect_to social_networking.social_networking_profile_path
      end
    end
POST /coach/groups/:group_id/moderates