refactor docker_engine dependency

molecule/centos7/converge.yml

@@ -1,11 +1,14 @@
 ---
-- name: Converge (Stage 1)
+- name: Converge
   hosts: all
-  roles:
+  environment:
-    - role: xoxys.python3
+    PYTHONPATH: /opt/python2/ansible-deps/lib/python2.7/site-packages
-    - role: xoxys.docker_engine
+  vars:
+    dockerengine_packages_extra:
+      - epel-release
+      - python-pip
+      - python-virtualenv
 
-- name: Converge (Stage 2)
-  hosts: all
   roles:
+    - role: xoxys.docker_engine
     - role: xoxys.docker_tidy