r? Update site design (from @gkoberger)

Close #61 with a design based on the mockup + PSD from @gkoberger.

I made some liberties with the conversion, and implemented what I thought
made sense for a responsive design.

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This is what I have so far, but it's not complete. Hopefully I'm on the right track.

![screenshot 2014-03-20 01 15 01](https://f.cloud.github.com/assets/90871/2469106/b2407500-afee-11e3-9251-f76e29e6247a.png)

**This is a work-in-progress, not everything is complete yet, especially the responsive bits.**