Updated siteconfig layout to be more like modeladmin

Before:
![schermafbeelding 2013-07-26 om 17 35 16](https://f.cloud.github.com/assets/1517053/863486/756a8966-f60a-11e2-8d0b-77c42c7f2c6d.png)

After:
![schermafbeelding 2013-07-26 om 17 46 18](https://f.cloud.github.com/assets/1517053/863491/8b090374-f60a-11e2-8641-4770a57552a6.png)

Fixes #808