Ensure that policy file has correct group/mode

When the policy file is copied from the templated
file to the active file, it loses its group/mode
settings. This patch ensures that they are properly
replicated during the copy.

Change-Id: I7a6c07cce405c8e7f3dca13cc24dc413895e6bfb

handlers/main.yml

@@ -119,6 +119,9 @@
   copy:
     src: "/etc/keystone/policy.json-{{ keystone_venv_tag }}"
     dest: "/etc/keystone/policy.json"
+    owner: "root"
+    group: "{{ keystone_system_group_name }}"
+    mode: "0640"
     remote_src: yes
   tags:
     - keystone-config