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/kubernetes/node/meta/main.yml

@@ -10,7 +10,12 @@ dependencies:
     file: "{{ downloads.install_socat }}"
     tags: [download, kubelet]
     when: ansible_os_family in ['CoreOS', 'Container Linux by CoreOS']
+  - role: download
+    file: "{{ downloads.kubeadm }}"
+    tags: [download, kubelet, kubeadm]
+    when: kubeadm_enabled
   - role: kubernetes/secrets
+    when: not kubeadm_enabled
     tags: k8s-secrets
   - role: download
     file: "{{ downloads.nginx }}"