Add required python-six package to installation

* Moves package list into a defaults/main.yml file
* Closes #3020

roles/openshift_facts/tasks/main.yml

@@ -10,11 +10,9 @@
 - set_fact:
     l_is_containerized: "{{ (l_is_atomic | bool) or (containerized | default(false) | bool) }}"
 
-- name: Ensure PyYaml and yum-utils are installed
+- name: Ensure various deps are installed
   package: name={{ item }} state=present
-  with_items:
-    - PyYAML
-    - yum-utils
+  with_items: "{{ required_packages }}"
   when: not l_is_atomic | bool
 
 - name: Gather Cluster facts and set is_containerized if needed

roles/openshift_facts/vars/main.yml

@@ -0,0 +1,7 @@
+---
+required_packages:
+  - iproute
+  - python-dbus
+  - python-six
+  - PyYAML
+  - yum-utils