Let's use systemd for EPEL 7
Moving from sys-V to systemd is disruptive and should normally not be done within a stable OS release, but since the ARC5 to ARC6 update is disruptive anyway doing this should be OK, I think. It should be done before the final release though. I asked on the ARC 6 suppord chat for feedback and so far got noone against it, and one (Andrej) in favour.