Add module commission_simple and commission_simple_sale

Improve view inheritance in account_usability

commission_simple/models/__init__.py

@@ -0,0 +1,7 @@
+# -*- coding: utf-8 -*-
+
+from . import commission
+from . import res_users
+from . import res_company
+from . import account_config_settings
+from . import account_invoice_line