Only do the update routine when the status changes for group_app's and role requests.
This helps prevent spamming multiple notifications.
Patch by: Lennard de Rijk
Reviewed by: to-be-reviewed
"""Multi-consumer multi-producer dispatching mechanism
Originally based on pydispatch (BSD) http://pypi.python.org/pypi/PyDispatcher/2.0.1
See license.txt for original license.
Heavily modified for Django's purposes.
"""
from django.dispatch.dispatcher import Signal