Bump k8s version from 1.6.2 to 1.7.3.

* Bumped k8s image version from 1.6.2 to 1.7.3.

Change-Id: I8c81757b4f8c0d816838dc34e9113d17119f31af
diff --git a/classes/cluster/sl_k8s_contrail/kubernetes/init.yml b/classes/cluster/sl_k8s_contrail/kubernetes/init.yml
index d71de79..dbaa26e 100644
--- a/classes/cluster/sl_k8s_contrail/kubernetes/init.yml
+++ b/classes/cluster/sl_k8s_contrail/kubernetes/init.yml
@@ -19,7 +19,7 @@
     kubernetes_calicoctl_image: docker-prod-virtual.docker.mirantis.net/mirantis/projectcalico/calico/ctl:latest
     kubernetes_calico_image: docker-prod-virtual.docker.mirantis.net/mirantis/projectcalico/calico/node:latest
     kubernetes_calico_cni_image: docker-prod-virtual.docker.mirantis.net/mirantis/projectcalico/calico/cni:latest
-    kubernetes_hyperkube_image: docker-prod-virtual.docker.mirantis.net/mirantis/kubernetes/hyperkube-amd64:v1.6.2-2
+    kubernetes_hyperkube_image: docker-prod-virtual.docker.mirantis.net/mirantis/kubernetes/hyperkube-amd64:v1.7.3-1
     kubernetes_netchecker_agent_image: quay.io/l23network/k8s-netchecker-agent:v1.0
     kubernetes_netchecker_server_image: quay.io/l23network/k8s-netchecker-server:v1.0