Rename dns_server, add var for selinux. (#1572)

* Rename dns_server to dnsmasq_dns_server so that it includes role prefix
as the var name is generic and conflicts when integrating with existing ansible automation.
*  Enable selinux state to be configurable with new var preinstall_selinux_state

roles/dnsmasq/tasks/main.yml

@@ -102,7 +102,7 @@
 
 - name: Check for dnsmasq port (pulling image and running container)
   wait_for:
-    host: "{{dns_server}}"
+    host: "{{dnsmasq_dns_server}}"
     port: 53
     timeout: 180
   when: inventory_hostname == groups['kube-node'][0] and groups['kube-node'][0] in ansible_play_hosts

roles/dnsmasq/templates/dnsmasq-svc.yml

@@ -18,6 +18,6 @@ spec:
       targetPort: 53
       protocol: UDP
   type: ClusterIP
-  clusterIP: {{dns_server}}
+  clusterIP: {{dnsmasq_dns_server}}
   selector:
     k8s-app: dnsmasq