Minor refactoring

[mikalaisyty]

First of all, thank you for the awesome samples! I was a visitor of the Open Codes exhibition at ZKM and saw your training session. It is just incredible how large is the amount of work done.

Please, consider this PR as an attempt to help. If you have any questions please do not hesitate to write comments or contact me directly. I would be happy if I could somehow contribute to any of the ZKM related projects.

Anyway this PR makes the following changes:

1. Removes surplus/duplicated .gitignore files.
2. Provides a better way to install Python dependencies with on sigle command.

Reference: https://pip.pypa.io/en/stable/user_guide/#requirements-files

The requirements.txt file can be generated automatically by using an Open Source project called pipreqs (https://github.com/bndr/pipreqs).

3. All corresponding changes are applied in README.md file.

[digital-codes]

thanks for the effort. Just 1 issue: pip should be pip3, right? I'm not going to deal with Python2