Gravity populate righthand component

This follows on from https://github.com/guardian/frontend/pull/2866 and populates the right hand component with links from gravity. 

I've extended the duration of test to run for two weeks from tomorrow

![gravity-recommended](https://f.cloud.github.com/assets/986155/2067534/d6d5b49e-8cfc-11e3-9bb7-014b047ece2c.png)