lxc-test-unpriv: test for different cgroups per subsystem

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
lxc-test-apparmor-mount: don't clear out /etc/lxc/lxc-usernet

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>