Ensure docker is running before dropping containers
Ensure docker is running before dropping containers

It might happen we have docker binary installed, while the docker
service isn't active/running. This would make the playbook fail,
while it's not a valid failure.

Change-Id: I3f3011e6855b38828644b94fac3f5e88edfc6d1a

openstack/tripleo-common,openstack/tripleo-common