_request(options, auth, path, callback) {
    options = options || {};

    auth = auth || this.auth;
    path = path || this.path || '';

    if (this.batch) {
      this._doBatch(options, callback, auth, path);
    } else {
      this._doRequest(options, callback, auth, path);
    }
  }
Make a request to a winstond server or any http server which can
handle json-rpc.
@param {function} options - Options to sent the request.
@param {Object?} auth - authentication options
@param {string} path - request path
@param {function} callback - Continuation to respond to when complete.