Prevent code overflowing container

This fix prevents code from overflowing its container in a post.

## Before:

![screenshot 2014-05-20 09 47 20](https://cloud.githubusercontent.com/assets/3824954/3027818/59770926-e026-11e3-8707-55254f7955bf.png)

## After:
![screenshot 2014-05-20 09 50 26](https://cloud.githubusercontent.com/assets/3824954/3027825/6b8169d6-e026-11e3-98c9-6971a258c451.png)