Add GeneratePodHostNameAndDomain() to RuntimeHelper to
get the hostname of the pod from kubelet.
Also update the logging flag to change the journal match from
_HOSTNAME to _MACHINE_ID.
This enables more fine-grained control over the things we want to
output. Also by closing the stdout/stderr of the journalctl process
when user hits `Ctrl-C` after `kubectl logs $POD -f`, this enables
the journalctl process to exit.
