Configure GitHub Actions to run Super-Linter

[lparsons]

This Pull Request sets up a GitHub Actions workflow that runs the GitHub Super-Linter on the entire codebase. It also formats the files according to the standards specified by the linters.

Super-Linter is a collection of bash scripts that run various "standard" linters for many different types of files. The hope is that this helps to:

• Prevent broken code from being uploaded to the default branch (main)
• Help establish coding best practices across multiple languages
• Build guidelines for code layout and format
• Automate the process to help streamline code reviews

The linters that are in use right now are:

• Markdown-lint - .markdown-lint.yml
• Flake8 - .flake8
• Pylint - .python-lint -> .pylintrc
• Black - .python-black - Note that black will actually reformat your code for you, so just run black . before committing to fix everything up.
• isort - .isort.cfg - isort also automatically formats files for you (isort .)

The python linters can all be installed via pip. To make it simpler to install them on a development machine, this PR creates a requirements/dev.txt file that can be used to create a virtual environment with the linters installed in addition to the core dependencies. Using requirements.txt or requirements/prod.txt will install only those things needed for production.

Finally, the configuration for the linters is borrowed from Super-Linter which attempts to provide some "best-practices" and also help ensure the linters all get along. There are two changes to the defaults:

• .isort.cfg
  • Added config to include our Django apps as first party packages. For some reason running under Super-Linter didn't do this in GitHub actions.
• .flake8
  • ignore E231 There should be whitespace after the characters ,, ;, and :. black; fixed in black 20 (flake8 error E231 after a successful black run psf/black#1289)

[hepcat72]

Nothing blocking.

[hepcat72]

Resolved all comments. Full speed ahead!