Add handle indication on search page, improve design

This comes after discussion on https://github.com/diaspora/diaspora/issues/4773
The search itself needs to be improved, but this already adds an indication to the user: if he doesn't find his friends, he should try to search them using their full handle.

I also changed the design a little bit, displaying the title as elsewhere.

Before
![before](https://f.cloud.github.com/assets/930064/2218357/2fc1574c-9a2d-11e3-9095-233433ca3f33.png)

After
![after](https://f.cloud.github.com/assets/930064/2218360/3297ce74-9a2d-11e3-8af3-67efb5e05b0b.png)

After (with results)
![after-contacts](https://f.cloud.github.com/assets/930064/2218362/36f7f67e-9a2d-11e3-95c3-c4efa20df28e.png)

I'm not sure where to place the text "Looking for posts tagged #thesearch?" when there are results, especially when it's paginated. Any suggestions?