优化了滑动冲突。review by luliang。

@@ -423,8 +423,8 @@ export default class Home extends Component {
 
     //因为android下拉刷新控件与swiper的滑动事件会引起冲突，所以将listview滚动位置加1以阻止下拉刷新
     _onChildScrollToPreventRefresh() {  
-        if(Platform.OS === 'android' && this.state.currentY < height && this.listView){
-            this.listView.scrollTo({x: 0, y: this.state.currentY + 1, animated: false});
+        if(Platform.OS === 'android' && this.state.currentY == 0 && this.listView){
+            this.listView.scrollTo({x: 0, y: 1, animated: false});
         }
     }