修复导航栈错误的问题 review by 盖剑秋

@@ -80,8 +80,12 @@ class PostingContainer extends Component{
     }
 
     componentWillUnmount() {
+        let key = this.props.navigationState.key;
+        let index = key.substring(0, 1);
+        if (index == 1) {
             Actions.refresh({key: 'Home', showNativeTabBar: true});
         }
+    }
 
     componentWillReceiveProps(nextProps) {
         if (this.props.posting.dataValid) {