This does not address per-node certs and scheduler/proxy/controller-manager
component certs which are now required. This should be handled in a
follow-up patch.
Also adds calico-rr group if there are standalone etcd nodes.
Now if there are 50 or more nodes, 3 etcd nodes will be standalone.
If there are 200 or more nodes, 2 kube-masters will be standalone.
If thresholds are exceeded, kube-node group cannot add nodes that
belong to etcd or kube-master groups (according to above statements).
