Add final runtime and disk usage summary to mail reports

install.sh

@@ -70,6 +70,7 @@ add lib/space.py /usr/local/lib/app-backup/space.py 640
 add lib/prepare-restore-test.sh /usr/local/lib/app-backup/prepare-restore-test.sh 640
 add lib/backup_set.py /usr/local/lib/app-backup/backup_set.py 640
 add lib/report.py /usr/local/lib/app-backup/report.py 640
+add lib/usage.py /usr/local/lib/app-backup/usage.py 640
 add systemd/app-backup.service /etc/systemd/system/app-backup.service 644
 # Preserve existing schedules. The new timer template remains available as .dist.
 if [[ -e /etc/systemd/system/app-backup.timer ]]; then