a little enahcement and update

[roadt]

1. Add dependencies / requirements.txt
2. use 'credentials' package to retrieve github user & token (~/credentails.json)
3. update mpv_script_directory.json to date (today)

[Nudin]

Thanks. I merged the first commit. I'm not sure yet how to handle the update of the directory, since there have also been edits to the directory in this repo.