Split deploy steps in separate playbooks: part1 (#3451)

* Fix bootstrap_os/ubuntu idempotency

* Update bastion role

* move container_engine in sub-roles

* requires ansible 2.5

* ubuntu18 as first CI job

roles/container-engine/docker/templates/http-proxy.conf.j2

@@ -0,0 +1,2 @@
+[Service]
+Environment={% if http_proxy is defined %}"HTTP_PROXY={{ http_proxy }}"{% endif %} {% if https_proxy is defined %}"HTTPS_PROXY={{ https_proxy }}"{% endif %} {% if no_proxy is defined %}"NO_PROXY={{ no_proxy }}"{% endif %}