bugfix: switch camera

jhlive/live-wechat.vue

@@ -200,6 +200,7 @@ export default {
       }
     },
     switchCarema() {
+      wx.createLivePusherContext().switchCamera();
       this.pusher.frontCamera = this.pusher.frontCamera=='front'?'back':'front';
       console.log(LOGTAG+'pusher',this.pusher);
     },