Similar to how systemd creates cgroups for all services, for purposes of
tracking, Finit now does the same. We also mount all available cgroups
in the /sys/fs/cgroup namespace.
This patch adds support for grouping processes in logical cgroups, like
systemd, and an `initctl ps` command to list the hieararchy.
Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
