Improve profile page design on mobile

This PR improves the design of the profile user. It was inspired by the design of the hovercard.
**Before**
![before](https://cloud.githubusercontent.com/assets/930064/3648988/6cc3ed8c-110e-11e4-9692-bce51a879fe1.png)

**After**
![after](https://cloud.githubusercontent.com/assets/930064/3648986/6c435f0a-110e-11e4-84e6-7d5e034cb9e1.png)

The space under the diaspora* ID is here to put the "Add to an aspect" dropdown selector, like on hovercards.

If the username is very long, it goes under. I thought cut it was not a good idea.
![long](https://cloud.githubusercontent.com/assets/930064/3648987/6c7d319e-110e-11e4-99cc-a3f927c26b34.png)