Add support for syntax highlighting the response body

This update turns a boring response body into something that you would like to take home to your mother.

Old:
![boring-response](https://f.cloud.github.com/assets/283234/2183624/a82157e8-97b0-11e3-871d-dbe800634012.png)

New:
![pretty-response](https://f.cloud.github.com/assets/283234/2183626/ac8eecdc-97b0-11e3-9889-d1603dc54009.png)