run-backup: do pre-snap by default

Signed-off-by: David Sterba <dave@jikos.cz>
Add quota helper scripts

Signed-off-by: David Sterba <dave@jikos.cz>
Add simple snapshot cleaner

Signed-off-by: David Sterba <dave@jikos.cz>
Add script to remove a snapshot

Signed-off-by: David Sterba <dave@jikos.cz>
Add time-base snapshot cleaner

Signed-off-by: David Sterba <dave@jikos.cz>