Homepage revamp

Extensive changes to the homepage, in both layout and content.

This builds on Mo's pull request: https://github.com/aeolusproject/aeolusproject.github.com/pull/81 but I went further as we had discussed doing a few weeks ago.

I think the content is a lot better, but I'm very much open to suggestions for further improvement. The layout changes are a one-time thing, but what really matters is perfecting the content here.