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.
I don't either but 41% of ocaml.org visitors are running windows so it would be nice to provide them with an easy path to install OCaml and opam — so that they can complain about packages not compiling! ;-)