Allow rsync-based deployments to web nodes

See also http://ci.theforeman.org/job/deploy_web_nocap/6/console for an example of it running

Lots of hardcoding here, but we're already hardcoding the site dir anyway, so it's fine. Feels like we can probably extra the rsync stuff into a module/define of it's own at some point - it's *very* similar to the freight stuff...