Adding truncation to football liveblogs

* Very rudimentary truncation

This is two fold - Football's requirements are pretty simple, and live blogs are being rehashed.

We can look at extending [`shouldTruncate`](https://github.com/guardian/frontend/compare/football-liveblog-truncation?expand=1#diff-78360b6b49c840a5052f32afe5da688cR18) to return a set of arguments for `truncate` dependant on factors. This seemed like over engineering for now.

# Show me the simple truncation
![truncate](https://cloud.githubusercontent.com/assets/31692/2697806/c52bad48-c3f2-11e3-980d-d72c1aefb00f.png)

---

![TRUNK](http://www.ohmagif.com/gif/0811/elephant-trunk-stunt.gif)