FIX: disorderly page when uploading multi files

处理了一下多文件上传后页面的显示效果

之前:
![screenshot 2014-04-28 15 33 37](https://cloud.githubusercontent.com/assets/1501364/2814343/85034072-cea7-11e3-8f51-099cc09a81b0.png)

之后:

![screenshot 2014-04-28 15 34 55](https://cloud.githubusercontent.com/assets/1501364/2814350/9bbfb48a-cea7-11e3-90ce-6d87ba295f84.png)