Added Survey From Field validation.
Also added the COMMENT_PREFIX in Survey model to ensure that comments are stored in the same way everwhere.
Reviewed by: Lennard de Rijk
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