Bump docker to 1.13.1 for k8s clusters.

Change-Id: I72e2a0792b561b3a156543b7b782d4e62f863aec
diff --git a/classes/cluster/k8s-aio-contrail/kubernetes/compute.yml b/classes/cluster/k8s-aio-contrail/kubernetes/compute.yml
index 37a004a..df61ea9 100644
--- a/classes/cluster/k8s-aio-contrail/kubernetes/compute.yml
+++ b/classes/cluster/k8s-aio-contrail/kubernetes/compute.yml
@@ -29,7 +29,7 @@
   docker:
     host:
       pkgs:
-        - docker-engine=1.12.6-0~ubuntu-xenial
+        - docker-engine=1.13.1-0~ubuntu-xenial
         - python-docker
       options:
         bip: 172.31.255.1/24