Fix #562 refactor YouTube tests.
- Refactored the youtube framework tests as suggested in #517.
- Reformatting multi-line dict and lists.
- Constant renamed to upper case.
- Refactored tests to use test case lists.
- get_defaults() test checks against an expected dict.
- Adding missing commas to items in list/dicts.
- Refactored some test cases to use pytest.
- Using capsys instead of sys.out for pytest fixtures.
Added todo list to the testing documentation page.
Updated configuring your environment for pytest.
Replaced lost work..
merge conflict resolved..