Restyle comment is free articles

Restyling the Comment is Free articles to match their treatment across the brand.

To Do: Add new commentDefault colour to pasteup-palette

![screen shot 2014-09-24 at 17 12 40](https://cloud.githubusercontent.com/assets/1607666/4391503/c5028d4e-4405-11e4-984d-add7b20041af.png)

I've added as a To Do, as @paulrobertlloyd was messing with pasteup-palette