Python package dependency management for building/development

[jbusche]

There's a problem with the current requirements.txt method as it pulls in too many requirements for CI/CD. We want to enable users to install minimal set of dependencies needed for functioning of the repository and to perform tuning techniques. Other dependencies should be optional.

This issue is to explore what best optional dependency framework to use to ensure install is light-weight.

Tasks include:

1. Explore how to enable optional dependencies - what are best practices open source repositories use
2. Add that framework to this repository with associated documentation

[Ssukriti]

some ideas from @hickeyma and Fabian is to use https://packaging.python.org/en/latest/specifications/pyproject-toml/

[hickeyma]

@jbusche There isn't a problems with requirements files per say. It is just that the implement optional dependencies using requirements files is clunky as you have to have separate files. The Python packaging provides a cleaner method where you can specify optional dependencies.

[jbusche]

OK, added pr #68 that hopefully addresses the issue...