修复导航栈错误的问题 review by 盖剑秋

@@ -80,7 +80,11 @@ class PostingContainer extends Component{
     }
 
     componentWillUnmount() {
-        Actions.refresh({key: 'Home', showNativeTabBar: true});
+        let key = this.props.navigationState.key;
+        let index = key.substring(0, 1);
+        if (index == 1) {
+            Actions.refresh({key: 'Home', showNativeTabBar: true});
+        }
     }
 
     componentWillReceiveProps(nextProps) {