listMembers(options, cb) {
      return this._request('GET', `/orgs/${this.__name}/members`, options, cb);
   }
List the users who are members of the company
@see https://developer.github.com/v3/orgs/members/#members-list
@param {object} options - filtering options
@param {string} [options.filter=all] - can be either `2fa_disabled` or `all`
@param {string} [options.role=all] - can be one of: `all`, `admin`, or `member`
@param {Requestable.callback} [cb] - will receive the list of users
@return {Promise} - the promise for the http request