Experiment to inject containers based on section history

As a zero-audience A/B test experiment (`#ab-HistoryContainers=show`) that pulls containers from sections you've engaged with, onto the network front. Currently pulls 3 containers by default above the Popular container.

The history analysis is provided by @stephanfowler's history module, the same that powers the "history tags" below the nav.

/cc @crifmulholland 

PS: I had some errors while compiling and had to amend the requirejs config. It looked sensible, but might be horribly wrong..?

![screenshot-fav-container](https://cloud.githubusercontent.com/assets/36964/5540793/ab58eb14-8ac7-11e4-9f2d-8f0aecd42e28.png)

`return historyContainers.hasHistory()`

Only include people in the AB test if they could actually see something, then give it a try on 1%...