[FIX] implicitly relative imports

__init__.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-import controllers
-import models
+from . import controllers
+from . import models

controllers/__init__.py

@@ -1,4 +1,4 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-import main
+from . import main

models/__init__.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-import sale_coupon_rule
-import sale_coupon_program
-import sale_order
+from . import sale_coupon_rule
+from . import sale_coupon_program
+from . import sale_order