Fix init script cgroup mounting workarounds to be more similar to cgroupfs-mount and thus work properly

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Add variable for DOCKER_LOGFILE to sysvinit and use append instead of overwrite in opening the logfile

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge pull request #4574 from tianon/fix-cgroup-hax

Fix init script cgroup mounting workarounds to be more similar to cgroupfs-mount...