Local facts are strings so make this explicit

This patch fixes the following ansible warning:

[WARNING]: The value True (type bool) in a string field was converted to
u'True' (type string). If this does not look like what you expect, quote the
entire value to ensure it does not change.

Change-Id: If5b462b551a037107b2396d1eb2fc879d4b2bfa9

playbooks/os-keystone-install.yml

@@ -141,6 +141,6 @@
         dest: "/etc/ansible/facts.d/openstack_ansible.fact"
         section: keystone
         option: "need_db_contract"
-        value: False
+        value: "False"
       when:
         - "dbsync_contract is succeeded"