Added black to Pipfile and black configuration to pyrpoject.toml

[tleonhardt]

Added black to Pipfile and black configuration to pyrpoject.toml

Also:

• Updated flake8 and isort config in setup.cfg to be consistent with black
• Simplified how flake8 is executed by invoke task
• Simplified how flake8 is executed by GitHub Actions workflow

This PR encompasses just the configuration changes present in the much larger PR #1052 - the point is to separate the configuration changes from the auto-generated changes made by black and isort

This partially addresses #930

[codecov]

Codecov Report

Merging #1053 (f691170) into master (918200c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1053   +/-   ##
=======================================
  Coverage   98.14%   98.14%           
=======================================
  Files          22       22           
  Lines        4630     4630           
=======================================
  Hits         4544     4544           
  Misses         86       86           

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[tleonhardt]

FYI the way the GitHub Status API works is messed up

I may try to use this commit to perform some low-level POST hackery to clear out old appveyor and travis statuses now that we aren't using them anymore but GitHub is still waiting for their freaking last status. But nothing I tried actually worked.

[tleonhardt]

@anselor @kmvanbrunt If neither of you object, I'm going to merge this in. It is really a preparation for the other larger PR which can allow others to experiment with the configuration for black, flake8, and isort

[anselor]

I'll try to see if I can run search across the code base to address my concerns over black and items per line