Add csv export support for Roles. If needed we will add support for extra properties in Mentor, Org Admin and Students models later.
Patch by: Pawel Solyga
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