Serve using Fastly

This is almost good to go. The only remaining issue is to [fix my broken VCL](https://gist.github.com/lmarburger/6531818) to transparently follow and cache redirects. I'm hoping @tyler has some answers. Once that's in place, you'll be able to add https://bundler.a.ssl.fastly.net as a source in rubygems and have specs and gems be served by Fastly's CDN.