Simple implementation to generate JWT tokens (only HMAC-SHA256)

The tests have been performed on my host (MicroPython v1.12 on 2020-04-18; darwin version) and on a WEMOS D1 Mini.

1. Install micropython
2. In a shell enter the following command

micropython src/main.py

1. Upload the 'src' content
2. The main.py will be executed after upload