cgroups: Add more cgroup options and fix systemd support

This adds a bunch more cgroup options for both raw and systemd
backend, and makes all the existing settings work again on systemd
backend.

This adds most of the properties exposed by systemd, as well
as some (cpu.cfs_quota_us) that are used by OpenShift.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)