Add k8s externaldns and coredns addons switchers

Those parameters needed to control deployment of externaldns and
coredns addons.
Also allowed to control externaldns image version and
base support of externaldns provider switch.
Externaldns and coredns disabled by default in any model.

Change-Id: I05fb713b7e7c053a990f4f3811a4c2042d420b36
diff --git a/classes/cluster/k8s-ha-calico-cloudprovider/kubernetes/init.yml b/classes/cluster/k8s-ha-calico-cloudprovider/kubernetes/init.yml
index 8baf8b1..b4aa8f8 100644
--- a/classes/cluster/k8s-ha-calico-cloudprovider/kubernetes/init.yml
+++ b/classes/cluster/k8s-ha-calico-cloudprovider/kubernetes/init.yml
@@ -45,6 +45,14 @@
     calico_private_network: 192.168.0.0
     calico_private_netmask: 16
 
+    # component docker images
+    kubernetes_externaldns_image: mirantis/external-dns:latest
+    kubernetes_externaldns_provider: coredns
+
+    # switches of addons
+    kubernetes_coredns_enabled: false
+    kubernetes_externaldns_enabled: false
+
     # OpenStack cloud provider
     openstack_auth_url: https://cloud-cz.bud.mirantis.net:5000/v3
     openstack_region_name: RegionOne