Changed to venv applaf2; updated requirements.txt
Added licensing boilerplate to files.

Google Python Style Guide recommends. Instead of including the
entire license, I just put a short sentence directing people
to the LICENSE.txt file.
Made PEP8 compliant.
Updated requirements.txt`
Updated README
Added Contributing section to README
Updated comments to match style guide.
Updated README
Updated README
Update requirements.txt. Add invoke