remove the said files when the package is deinstalled as the user may
wish to keep the files across upgrades. A message is printed advising the
user to remove the files manually if the packages is uninstalled permanently.
* run from a central host
* scan clients for new ZFS filesystems
* manage varying desired backup intervals (per host) for
o full backups
o incremental backups
* maintain varying retention policies (per host)
* summarize existing backups
* restore any host:fs backup at any point in time to any target host
