code: function getStatus(url) {
    var client = new HttpClient(url);
    var executor = new Executor(client);
    var command = new Command(CommandName.GET_SERVER_STATUS);
    return executor.execute(command);
  }
docs: Queries a WebDriver server for its current status.
  @param {string} url Base URL of the server to query.
  @return {!Promise<!Object>} A promise that resolves with
  a hash of the server status.