Remove dependency from docker/pkg/systemd

Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com>
Merge pull request #159 from LK4D4/remove_docker_systemd_dep

Remove dependency from docker/pkg/systemd
Return NotFound error for cgroups abs paths

Signed-off-by: Michael Crosby <michael@docker.com>
Change not found error to be typed with cgroup subsystem

Signed-off-by: Michael Crosby <michael@docker.com>
Ignore not found erros in Paths

Signed-off-by: Michael Crosby <michael@docker.com>
Merge pull request #161 from crosbymichael/return-notfound-err

Return NotFound error for cgroups abs paths