Ensure k8s_etcd.get_cluster_size works for multi-master
Ensure k8s_etcd.get_cluster_size works for multi-master

If we had enough masters to form a etcd cluster, we would end up returning
"None" from this method, preventing the cluster formation.

ereslibre/salt,ereslibre/salt,ereslibre/salt,kubic-project/salt,kubic-project/salt,kubic-project/salt