add use_journal if we are enabling systemd
add use_journal if we are enabling systemd

This is going to be a new option in oslo.log, which we can start
setting early to make it take effect.

Change-Id: If0e5e4717a1810c759058f33608fbac7543f2d85

openstack-dev/devstack,noironetworks/devstack,group-policy/devstack,dtroyer/devstack,richliu/devstack,noironetworks/devstack,richliu/devstack,nawawi/openstack,group-policy/devstack,dtroyer/devstack,openstack-dev/devstack,nawawi/openstack