还原ios刷新的机制。review by 孙凯

@@ -33,7 +33,7 @@ export default class Message extends Component {
           this.viewDidAppear = DeviceEventEmitter.addListener(
             'VCDidAppear',
             () => {
-                this.props.onRefresh && this.props.onRefresh();
+                this.trigggePullToRefresh();
             }
         );