Atom feed should have absolute uris

I didn't actually check out this code to test it (I don't have a working vm with Mirage right now) but I'm a lurker and the relative links in the Atom feed were starting to bug me. I'm open to other ways to accomplish this if there's a better one.
Merge pull request #30 from mthurman/patch-1

Atom feed should have absolute uris
Add support for retrieving a deployment key for mirage/mirage-www-deployment
Merge branch 'travis-senv'

Conflicts:
	.travis-ci.sh
	.travis.yml
resolve more merge conflicts
whitespace
fix travis.yml post merge
travis: opam config env
Tweak installation instructions