Upgrade kubernetes to v1.12.0 (#3410)

* Upgrade kubernetes to v1.12.0

Use kubeadm v1alpha3 config

* Upgrade coredns and etcd

* Upgrage docker to 18.06

roles/kubernetes/kubeadm/templates/kubeadm-client.conf.v1alpha3.j2

@@ -0,0 +1,23 @@
+apiVersion: kubeadm.k8s.io/v1alpha3
+kind: JoinConfiguration
+clusterName: {{ cluster_name }}
+discoveryFile: ""
+caCertPath: {{ kube_config_dir }}/ssl/ca.crt
+discoveryTimeout: {{ discovery_timeout }}
+discoveryToken: {{ kubeadm_token }}
+tlsBootstrapToken: {{ kubeadm_token }}
+token: {{ kubeadm_token }}
+discoveryTokenAPIServers:
+{% if groups['kube-master'] | length > 1 and kubeadm_config_api_fqdn is defined %}
+- {{ kubeadm_config_api_fqdn }}:{{ loadbalancer_apiserver.port | default(kube_apiserver_port) }}
+{% else %}
+- {{ kubeadm_discovery_address | replace("https://", "")}}
+{% endif %}
+discoveryTokenUnsafeSkipCAVerification: true
+nodeRegistration:
+  name: {{ inventory_hostname  }}
+{% if container_manager == 'crio' %}
+  criSocket: /var/run/crio/crio.sock
+{% else %}
+  criSocket: /var/run/dockershim.sock
+{% endif %}