fix user/username error class and add alert indicator left border


![screenshot 2014-05-16 21 52 17](https://cloud.githubusercontent.com/assets/297343/2997874/4c851c1e-dd04-11e3-9c86-ede95ac5ca09.png)
![screenshot 2014-05-16 21 52 42](https://cloud.githubusercontent.com/assets/297343/2997853/253e427a-dd04-11e3-9812-b0a18c1b8e67.png)

huge diff because of formatter. just checkout .alert part.

I moved previous css for .alert, combine them. And moved them to common. That's all.