WIP: Make sure network does come up correctly after reboot

This is not ready for being merged yet, but it would still be good if people could give it some thoughts.

It needs especially more testing in a HA setup to make sure it does not interfere with the virtual IPs managed by pacemaker (like we experienced in https://github.com/crowbar/barclamp-deployer/commit/ff6181c496bf6c083145d0900d6febc11a1b6e84).