Improve UI for superusers (bug 1100533)

Previously, superusers were shown nothing in particular. Now:

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### Superusers:

![admin](https://cloud.githubusercontent.com/assets/23885/5204851/f72df2b0-754f-11e4-99c7-60c1d32ad2d0.png)

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### Regular users:

![nonadmin](https://cloud.githubusercontent.com/assets/23885/5204849/f4da0008-754f-11e4-8104-bb10b5f2f71b.png)