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
Coverage: code coverage testing for Python
Coverage.py is a Python module that measures code coverage during test execution.
It uses the code analysis tools and tracing hooks provided in the Python standard
library to determine which lines are executable, and which have been executed.
For more information, see http://nedbatchelder.com/code/modules/coverage.html