UPSTREAM: <carry>: Tolerate node ExternalID changes with no cloud provider

Previously, if the kubelet tried to register itself with the API server,
and was rejected due to the external ID changing, it would delete the
node object and recreate it.  This commit causes it to tolerate
a change in ExternalID when the ExternalID is not being provided by a
cloud provider, assuming the new ExternalID is either the node's
(metadata) name, or one of node's addresses.

Author: pmorie