Merge "Refactor and optimise image pulling"

ansible/roles/aodh/tasks/pull.yml

ansible/roles/barbican/tasks/pull.yml

ansible/roles/blazar/tasks/pull.yml

ansible/roles/ceilometer/tasks/pull.yml

ansible/roles/chrony/tasks/pull.yml

ansible/roles/cinder/tasks/pull.yml

ansible/roles/cloudkitty/tasks/pull.yml

ansible/roles/collectd/tasks/pull.yml

ansible/roles/common/tasks/pull.yml

ansible/roles/cyborg/tasks/pull.yml

ansible/roles/designate/tasks/pull.yml

ansible/roles/elasticsearch/tasks/pull.yml

ansible/roles/etcd/tasks/pull.yml

ansible/roles/freezer/tasks/pull.yml

ansible/roles/glance/tasks/pull.yml

ansible/roles/gnocchi/tasks/pull.yml

ansible/roles/grafana/tasks/pull.yml

ansible/roles/hacluster/tasks/pull.yml

ansible/roles/haproxy/tasks/pull.yml

ansible/roles/heat/tasks/pull.yml