Wrap long code blocks

Basically don't want this to happen:

![screen shot 2013-09-26 at 9 40 05 pm](https://f.cloud.github.com/assets/4161981/1217870/42325164-26b1-11e3-985d-3d6a7e2dedc2.png)

Also useful for long 1-liners like bookmarklets.