added mandatory info to list

Added the mandatory Information to the Attribut List.

I have tried both `*` and the Label `Mandatory`. For me `Mandatory` is better, but i can change it to `*`.
I don't mind ;)

![screenshot 91](https://cloud.githubusercontent.com/assets/1867177/4062842/040e8ba0-2e03-11e4-9118-3d673a12039b.png)