Breaking news

![screenshot](https://cloud.githubusercontent.com/assets/1147913/3800991/0f73b1fc-1bff-11e4-8840-dfee286b4cb0.png)

Consumes `/breaking-news/lite.json` and decides which item to display from it - if any - based on page section, primary keyword, and the user's histogram of visits to these.
Use the [rem mixin](https://github.com/guardian/frontend/blob/master/common/app/assets/stylesheets/components/guss-rem/_rem.scss).