load(_request) {
    var request = _request || this.request || utils_request;
    var loading = new core["defer"]();
    var loaded = loading.promise;

    if (this.contents) {
      loading.resolve(this.contents);
    } else {
      request(this.url).then(function (xml) {
        // var directory = new Url(this.url).directory;
        this.document = xml;
        this.contents = xml.documentElement;
        return this.hooks.content.trigger(this.document, this);
      }.bind(this)).then(function () {
        loading.resolve(this.contents);
      }.bind(this)).catch(function (error) {
        loading.reject(error);
      });
    }

    return loaded;
  }
Load the section from its url
@param  {method} [_request] a request method to use for loading
@return {document} a promise with the xml document