0install blog draft

This pull request is to track the 0install blog post. Notes:

1. It's currently blocked on getting the DNS entry added, so you can't follow along currently. We need this entry added:

   tools.ocaml.org -> CNAME ocaml.github.io

2. The easiest way to see the images seems to be to symlink them into the root locally.
Will http://tools.ocaml.org/opam.xml appear as a link??