Modified the timeout logic in create_image to track the image creation progress
(size) rather than simply waiting a certain amount of time.  Also changed the
code to report progress at regularly spaced intervals (adjustable), and
to indicate when the timeout timer has been activated, or halted due to
progress.  The changes also include an NFS cache slack factor, which makes
the effective non-progress timeout equal to the sum of the slack time, plus
the non-progress time (currently 3 + 5 = 8 minutes).

Some changes were made to the error and cleanup logic to help revert the
state of the DB and node as much as possible (node is not rebooted if the
DB state cannot first be reverted) prior to exit.