ui changes to the search box

- add a `details` field to a search suggestion - use that info to style the search results
- normalize fonts a bit, and make the search box slightly wider

@yjbanov 

I'm not 100% sure of the use of `@observable`. I don't think I want those two suggestion fields to be observable, I just want to make sure that dart2js doesn't tree shake them away.

![screen shot 2014-01-28 at 9 07 33 am](https://f.cloud.github.com/assets/1269969/2022626/7aa5610c-8850-11e3-9453-89fb02d01d18.png)