Fix theming controlpanel styles

@buchi It's not exactly the onegov-style, but it's operable :wink: 

**from**
![bildschirmfoto 2014-04-04 um 12 07 38](https://cloud.githubusercontent.com/assets/157533/2614094/3e214c18-bbe1-11e3-938c-66202b9aaa43.png)

**to**
![bildschirmfoto 2014-04-04 um 12 07 30](https://cloud.githubusercontent.com/assets/157533/2614095/3e2164aa-bbe1-11e3-83f3-4abb781684ff.png)


fixes #78