updatedb: support lower zoom expiration

osm-expconv:
 - now support lower zoom
   you should call it with
   $osm-expconv mapname minzoom maxzoom
   such as  example 12 18

osm-updatedb:
 -update for osm-expconv change
etc/osmdb.conf:
 - add MINZOOM, MAXZOOM and FILTER parameters

data/expire_list.example:
  for test purpose

Signed-off-by: Hiroshi Miura <miurahr@linux.com>