Update the way version numbers are set for packages

[fhightower]

Every Democritus library should:

• Use setuptools_scm to pull version for version control system.
• Update library's init.py to pull version from setup.py using importlib (or importlib_metadata for python < 3.8) as described here

(see https://github.com/fhightower-templates/python-project-template/issues/6 for more details)