Dont require pg_admin_password unless we're using it.

installer/roles/check_vars/tasks/check_openshift.yml

@@ -46,3 +46,10 @@
     - docker_registry_password is defined and docker_registry_password != ''
     msg: "Set the value of 'docker_registry_password' in the inventory file."
   when: dockerhub_base is not defined
+
+- name: pg_admin_password should be defined
+  assert:
+    that:
+      - pg_admin_password is defined and pg_admin_password != ''
+  when:
+    - pg_hostname is not defined or pg_hostname == ''