HTTP Cache template, based on squid

This cache is specially adapted to cache the big files that you download
when you're using Panamax, Docker & Vagrant with CoreOS.  It caches much
bigger files than caches normally cache, and it doesn't bother caching the
small files which can be downloaded really quickly anyway, and would just
take a lot of resources to track.

Designed for modern connections & modern containerized architectures!
Merge pull request #74 from justinsb/master

HTTP Cache template, based on squid