- Comment table names will now 'roll forward' as new ones are created
    - Restricted names to 3 characters, allowing for 26^3 (17576) possible names
- Removed unused AstroDB.comment_table_exists method and associated test
- Modified the existing test for AstroDB.create_unique_table_name to account for new functionality
    - Added 2 mock classes in the new tests/astro_mocks.py file
        - MockSqlite3Connection
        - MockSqlite3Cursor
    - Added a fixture mock_sqlite3_connect to utilize the above mock classes to mock the database
        - I should now have full control over the database with this fixture

- Modify tests to account for new error handling
- Add fixture to mock database returning None to simulate record not found
- Add static method YouTubeDataAPI.valid_video_id to aid in error checking