remove setupDev from libcontainer

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
add test

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
Merge pull request #4942 from vieux/cleanup_dev_libcontainer

remove setupDev from libcontainer