adding confirm_status in devices

ereuse_devicehub/resources/device/models.py

@@ -262,6 +262,13 @@ class Device(Thing):
             action = self.last_action_of(*states.Trading.actions())
             return states.Trading(action.__class__)
 
+    @property
+    def confirm_status(self):
+        """The actual state of confirmation of one Trade, or None if no Trade action
+        has ever been performed to this device."""
+        # TODO @cayop we need implement this functionality
+        return None
+
     @property
     def physical(self):
         """The actual physical state, None otherwise."""