Mitx addition/cg/gunicorn conf

It wasn't quite a clean merge, but it does work and fixes a bunch of our gunicorn <-> nginx issues. @bdero if you could take a look and maybe test against a sandbox.
In the long trip these vars make from YAML to JSON to Python key-values when the environment is initialized, do these end up being interpreted by the environment as a None type down the line, or do they remain a string that says "None", and if so, is that intended and okay?