Homepage revamp

I'd like to clean up the bottom half of the page as well, but avoiding huge PR. ;)

![image](https://cloud.githubusercontent.com/assets/1153134/5156748/30e4b1ca-7293-11e4-8a29-0801a26f3205.png)

cc @andrew it seems like the tests don't like octicon, would you help taking a look?
Space inside square brackets detected.