Search chrome

@stephanfowler a few changes requested by @twobobswerver 

Still to-do at some point, 

- @kungpochicken needs to cost the removal of adverts
- We'll build a route to guardian.co.uk/search & look at accessibility and non-javascript versions

Neither of these should block release.

![search](https://f.cloud.github.com/assets/84996/300353/110fb890-9595-11e2-9fb0-3c1401565e00.png)