Added request creation and processing to role.py.
This is used if you want to request to become a certain role for a group. For instance becoming a club member.
The process request view will also be used to cancel outstanding invites might this be necessary.
Patch by: Lennard de Rijk
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