Implement environment specific controls

[campb303]

Several pieces of the project need some settings changed to move from development to production. Both the Python codebase through gunicorn and Flask and the React frontend through node's process.env package support reading logic from .env files.

To avoid needless issues when changing environments and to allow environment secrets to be stores outside of version control, environment file reading support should be integrated into the project.

This can start with webserver configuration as described in this article.

[campb303]

This was implemented in #15 using Python's dotenv library. Closing.