Improve kops get instances when api is unavailable
Improve kops get instances when api is unavailable

When the api is unavailable, kops will say all the nodes have not yet
joined the cluster. That is not the case simply because e.g the admin
credentials have been expired. This PR makes it a bit more clear that we
cannot know the node name when the API is unavailable.

kubernetes/kops,kubernetes/kops,justinsb/kops,justinsb/kops,justinsb/kops,kubernetes/kops