update elements and fix some bugs

lib/src/google-apis/google-client-loader.html

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 <link rel="import" href="../polymer/polymer.html">
@@ skipping 59 matching lines @@
        * @event google-api-load-error
        */
 
       properties: {
         /**
          * Name of the API to load, e.g. 'urlshortener'.
          *
          * You can find the full list of APIs on the
          * <a href="https://developers.google.com/apis-explorer"> Google APIs
          * Explorer</a>.
-         * @required
          */
         name: String,
 
         /**
          * Version of the API to load, e.g. 'v1'.
-         * @required
          */
         version: String,
 
         /**
          * App Engine application ID for loading a Google Cloud Endpoints API.
          */
         appId: String,
 
         /**
          * Root URL where to load the API from, e.g. 'http://host/apis'.
@@ skipping 121 matching lines @@
             _statuses[this.name] = 'loading';
             _loaders[this.name] = this;
             gapi.client.load(this.name, this.version,
                 this._handleLoadResponse.bind(this), root);
           }
         }
       }
     });
   })();
 </script>