Darker Code Highlights: Zenburn

It is a nice scheme.

If any elements that should be highlighted are not, we can customize it before release.

Here is what it looks like:

![Screen Shot 2012-12-28 at 4 05 27 PM](https://f.cloud.github.com/assets/5411/34151/327a0d3e-5100-11e2-985a-fe626f604067.png)

![Screen Shot 2012-12-28 at 4 13 55 PM](https://f.cloud.github.com/assets/5411/34163/96e9cbbe-5101-11e2-858f-d3e7259bc1ce.png)

![Screen Shot 2012-12-28 at 4 14 30 PM](https://f.cloud.github.com/assets/5411/34164/9b1c2f74-5101-11e2-99a4-239d68d32943.png)