Re-introduced nginx and gunicorn servers for v2.0; included a README section on testing with them locally.

<h3>Substantive Changes:</h3>

- Made a new gunicorn.sh file with SOME of the basic functionality required for running the Flask app on the server. Enough so that you can run the Flask app. Some of the command line parameters will have to be re-introduced. Note that doing so required adding Gunicorn to project reqs; otherwise, it's incompatible with Python3
- Nginx.conf file added back to project, unchanged from master branch version, for now... made sure it was compatible with Gunicorn server.

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- Also added a README section on how to test the application directly on nginx and gunicorn servers, locally.