switch debian8-canal-ha to ubuntu

roles/kubernetes/master/tasks/main.yml

@@ -52,6 +52,8 @@
 
 - name: Create kube system namespace
   command: "{{ bin_dir }}/kubectl create -f {{kube_config_dir}}/{{system_namespace}}-ns.yml"
+  retries: 4
+  delay: "{{ retry_stagger | random + 3 }}"
   changed_when: False
   when: kubesystem|failed and inventory_hostname == groups['kube-master'][0]
   tags: apps