staging: Add staticmethod create_service in Factory.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
virt: Adapt nfs to Factory of service.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
staging: adapt utils_cgroup to Factory in service.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
virt: adapt lvsbs to Factory in service.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>