Deletes CRM_Volunteer_BAO_Need::delete()...

... which does not appear to be in use at all. Should eliminate the "Strict warning: Declaration of CRM_Volunteer_BAO_Need::delete() should be compatible with DB_DataObject::delete($useWhere = false) in require_once() (line 36 of .../civivolunteer/CRM/Volunteer/BAO/Need.php)" notice.