code: function (driver, response, remote, options, deferred) {
        return driver[(response.statusCode === 500 ? '_onError' : '_onSuccess')].bind(this)(driver, response, remote, options, deferred);
      }
docs: Response end callback function
  
  @method _onResponseEnd
  @param {DalekJs.Internal.Driver} driver Driver instance
  @param {object} response Response from the webdriver server
  @param {object} remote Dummy request body (function name, url, method)
  @param {object} options Request options (method, port, path, headers, etc.)
  @param {object} deferred Webdriver command deferred
  @chainable
  @priavte