kubeadm support (#1631)

* kubeadm support

* move k8s master to a subtask
* disable k8s secrets when using kubeadm
* fix etcd cert serial var
* move simple auth users to master role
* make a kubeadm-specific env file for kubelet
* add non-ha CI job

* change ci boolean vars to json format

* fixup

* Update create-gce.yml

* Update create-gce.yml

* Update create-gce.yml

roles/network_plugin/calico/templates/calico-node.yml.j2

@@ -19,7 +19,7 @@ spec:
         k8s-app: calico-node
       annotations:
         scheduler.alpha.kubernetes.io/critical-pod: ''
-        kubespray.etcd-cert/serial: "{{ etcd_node_cert_serial }}"
+        kubespray.etcd-cert/serial: "{{ etcd_client_cert_serial }}"
     spec:
       hostNetwork: true
 {% if rbac_enabled %}