[IMP] stock_usability: add tracking on lot fields (model already inherit from mail.thread)

stock_usability/models/__init__.py

@@ -4,6 +4,7 @@ from . import stock_picking
 from . import stock_picking_type
 from . import stock_warehouse_orderpoint
 from . import stock_quant
+from . import stock_lot
 from . import procurement_group
 from . import procurement_scheduler_log
 from . import product