This patch add a way to choose container engine inside tool and test
scripts. This is in preparation for Podman introduction but still
leaves Docker as default container engine.

Signed-off-by: Martin Hiner <m.hiner@partner.samsung.com>
Change-Id: I395d2bdb0dfb4b325b6ad197c8893c8a0f768324

Without these jobs, a compute node that is rebooted or powered off may
violently kill off the VMs running inside of it. This has been kept
separate from the main portion of kolla-ansible since no current role
modifies the systemd jobs of the system.

Change-Id: I0a4424f97b5ad872ff0398258c1dc42d31d0ef07