listMembers(options, cb) {
      log(`Getting members of Team ${this.__teamId}`);
      return this._requestAllPages(`/teams/${this.__teamId}/members`, options, cb);
   }
List the users who are members of the Team
@see https://developer.github.com/v3/orgs/teams/#list-team-members
@param {object} options - Parameters for listing team users
@param {string} [options.role=all] - can be one of: `all`, `maintainer`, or `member`
@param {Requestable.callback} [cb] - will receive the list of users
@return {Promise} - the promise for the http request