Add etcd-events cluster for kube-apiserver (#2385)

roles/etcd/defaults/main.yml

roles/etcd/handlers/main.yml

roles/etcd/tasks/configure.yml

roles/etcd/tasks/install_docker.yml

roles/etcd/tasks/join_etcd-events_member.yml

roles/etcd/tasks/join_etcd_member.yml

roles/etcd/tasks/main.yml

roles/etcd/tasks/refresh_config.yml

roles/etcd/tasks/set_cluster_health.yml

roles/etcd/templates/etcd-events-docker.service.j2

roles/etcd/templates/etcd-events-host.service.j2

roles/etcd/templates/etcd-events.env.j2

roles/etcd/templates/etcd-events.j2

...tes/master/templates/manifests/kube-apiserver.manifest.j2

roles/kubespray-defaults/defaults/main.yaml

roles/reset/tasks/main.yml

tests/files/gce_centos7-flannel-addons.yml