Disable actually pushing to the registry via dns for now

We need to sort out how to know that the registry certificate has the
proper hostnames attached to it. It will for 3.6 clean installs but not
for 3.5 to 3.6 upgrades. For now make it opt in and come back to
this.

roles/openshift_master/templates/atomic-openshift-master.j2

@@ -1,6 +1,6 @@
 OPTIONS=--loglevel={{ openshift.master.debug_level | default(2) }}
 CONFIG_FILE={{ openshift_master_config_file }}
-{% if openshift_use_dnsmasq | default(true) %}
+{% if openshift_use_dnsmasq | default(true) and openshift_push_via_dns | default(false) %}
 OPENSHIFT_DEFAULT_REGISTRY=docker-registry.default.svc:5000
 {% endif %}
 {% if openshift.common.is_containerized | bool %}