[WIP] HA with HAProxy

This is based on https://github.com/SUSE-Cloud/barclamp-keystone/pull/2 but adds some stuff for haproxy support.

Opening the pull request just to get some review.

This also depends on https://github.com/SUSE-Cloud/barclamp-crowbar/pull/15 and https://github.com/crowbar/barclamp-pacemaker/pull/12