def paste(action)
    @item.send(action, @target_folder)
    clipboard.remove(@item)
    redirect_to folder_url(params[:folder_id])
  rescue ActiveRecord::RecordInvalid
    redirect_to folder_url(params[:folder_id]), :alert => t("could_not_#{action}", :type => t(params[:type]))
  end
@item is set in require_existing_item
@target_folder is set in require_existing_target_folder