Bug 11484: Add option to cleanup_database.pl to purge Z39.50 search records from...

Bug 11484: Add option to cleanup_database.pl to purge Z39.50 search records from reservoir

It would be good to be able to specifically target import records from
Z39.50 for cleanup.

Test Plan:
1) Apply this patch
2) Import one or more batch record sets into Koha
3) Perform some Z39.50 searches
4) Run this command: misc/cronjobs/cleanup_database.pl -v --z3950
5) Verify that only Z39.50 records were deleted

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>