override_waffle_flag can now be used as a context manager in addition to its previous role as a decorator. Additionally, the tests have been updated to use standard assertions since we now use py.test.
This includes several general enhancement in addition
to the fixes for unified_course_view:
1. Add support for default when no waffle flag defined.
2. Add support for table_blacklist to assertNumQueries.
3. Rename flag to 'course_experience.course_outline_page'.
4. Change flag default to True when it is not defined.
