Deliver notification info

Created by: stefanoborini

Notification system to communicate to the UI and other entities interested in notification.

force_bdss/core_plugins/dummy/dummy_notification_listener/tests/test_dummy_notification_listener_model.py

 import unittest
 
-from envisage.plugin import Plugin
-
 from force_bdss.core_plugins.dummy.dummy_notification_listener\
     .dummy_notification_listener_factory import \
     DummyNotificationListenerFactory