There is a somewhat trivial issue with XendCheckpoint.py right now in

There is a somewhat trivial issue with XendCheckpoint.py right now in
that it logs everything written to stderr by xc_save and xc_restore as
errors whereas in fact the vast majority of this output is
information/debug (and all actual errors are marked by the string ERROR:
at the start of the message) -- this is confusing to folks looking at
the logs and makes automated log analysis tricky.

Fix is to scan for the ERROR: string and log anything without it using
log.info instead.

Signed-off by: Simon Graham <Simon.Graham@stratus.com>