Group detail page basics

This pull implements basic view and edit functionality for Groups.

The rough layout was inspired by the wireframes.

I followed an often used convention of using ``/model/{id}/edit/`` as the url for displaying the form. The form POSTs back to ``/model/{id}/edit/`` and then redirects to ``/model/{id}/`` on success.
I did it this way to match the wireframe

![screen shot 2014-12-04 at 11 46 49 am](https://cloud.githubusercontent.com/assets/17363/5303944/49806262-7bab-11e4-840a-00bd878a1ea7.png)