Make the image(s) compatible with Python 3

[richieadler]

Given Python 2 impending EOL, it's only natural to want to have an image with which to develop web2py apps in Python 3.

[davi-ga]

Given Python 2 impending EOL, it's only natural to want to have an image with which to develop web2py apps in Python 3.

Hello my dear, I remade the docker model using Python 3 and Web2Py 2.2.
Here is the link: https://github.com/Davi-Ga/web2py-davig