Render notifications in queue.
@private
function render(req, res, next)  {
    if (!req.session[sessionName].length) {
      next();
    } else {
      const resultHTML = [];
      async.each(
        req.session[sessionName],
        function(item, next) {
          beforeSingleRender(item, function(error, item) {
            if (error) return next(error);
            app.render(viewName, item, function(error, html) {
              if (error) return next(error);
              resultHTML.push(html);
              next(null);
            })
          })
        },
        function(error) {
          if (error) return next(error);
          req.session[sessionName].length = 0;
          afterAllRender(resultHTML, function(error, html) {
            if (error) return next(error);
            res.locals[localsName] = html;
            next();
          })
        }
      )
    }
  }