The script runs some SQL which ultimately determines the time at which the last
backup with an exit code of zero was. If there has never been a successful
backup, we ended up reporting a clear dot. Whilst this may lead to a few
transitory red dots immediately after adding a new host, I think this is
preferable to not realising for months that a host isn't being backed up!
See ticket 154527

For offline machines, use the time between last backup and last change of conn dot status to decide on backup status

This seems to be used for machines with postgres. It was also updated
to put exclude and log files in the new locations.

debian-zfs doesn't exist in Ubuntu.

Split logs for tasks with same target machine but different target filesystems into
different logfiles for easier debugging.

prepare-nondebian script creates a fake excludes file for the machine now if
one doesn't exist, because I keep forgetting to do it myself for Redhat
machines and then the zfs-rsync script fails.

Add missing log directory /var/log/chem-zfs-backups
Add missing dep on rsync
Add fakeroot to Makefile to allow non-root building