[FIX] portal: avoid errors during autovacuum

When the cron for autovacuum runs, the osv_memory objects are deleted. The portal.wizard.user object has a required field (wizard_id) linked to another osv_memory object (portal.user) which causes a traceback when the cron tries to delete portal.user object before the portal.wizard.user. opw 609918
[FIX] configuration file dbfilter's option has no effect

lp bug: https://launchpad.net/bugs/940439 fixed

bzr revid: fme@openerp.com-20140508075025-yszqmzie1z4n7l4j