remove displayed raw state

the raw state is obviously seen when we have slow internet connection and it will flashed {{authService.user.username}}, so according to ngBind doc, we should use ng-bing to resolve this issue.
http://docs.angularjs.org/api/ng.directive:ngBind

Below are the screenshot when the raw state is displayed:
![flashed-2013-09-18 22 19 08](https://f.cloud.github.com/assets/863947/1167386/8650e22c-208d-11e3-972f-e869650e182a.png)