[FIX] Impossible to delete an account even if it's not linked to any partner, this is because, that account was configured for that partner and hence the properties(ir.property) were created and those properties were still refering that account, to allow deletion of such accounts, this properties should be deleted when the resource(partner) was removed. (Maintenance Case: 586600)
[MERGE] OPW 586600: orm: delete a record properties when deleting the record.

  backport of v6.1 server revision-id: vmt@openerp.com-20120110160933-cjmk63dtb27rb0qp