Ensure tasks aren't empty dicts
Ensure tasks aren't empty dicts

Ansible doesn't like it when tasks are empty dicts so let's make sure
we aren't passing an empty dict in to the ansible tasks. Unfortunately
since we're validating non-heat processed yaml, the list_concats end
up being dicts to the yaml validator so we can't just ensure they are
always lists.

Change-Id: I13dcc4f3d4ea2ac4c7ab62887dfea293246f6530
Related-Bug: #1768019

dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates