Add olso privsep initialization related to patch 505701
Add olso privsep initialization related to patch 505701

In patch 505701 (Bug 1717582), the namespace code was changed from
running the OS commands directly to running under privileges separation.
As we do not initialize the privsep, tests fail (namely
fullstack.test_apps.TestSNat.test_icmp_ping_pong_with_external_peer)

Change-Id: If228cdc1183395ab8275e40f64c129cdf5632b73

openstack/dragonflow,openstack/dragonflow,openstack/dragonflow