fixed formatting issues, added support for screenshot.py

- Fixed formatting issues identified by PEP8 checker, 
- Incorporated comments from @khandelwal 
- Modified class constructors to include a test directory to store images generated by screenshot.py
I don't think this line executes. The return will simply return None which will evaluate to False in an if later down the line. I think to make this work you might need to put parentheses around the equality check.