V2.0 dev -- prepped a v2.0 flask app with gunicorn script, nginx conf, and simplified routing

- cleaned up app.py, by moving static files elsewhere and
- made basic gunicorn script to flask app
- set up short README guide to test app on nginx and gunicorn servers
- made an nginx script ready to be included in a master nginx configuration file
- the one API endpoint so far '/api/2.0/version' became '/version' internally, so that it can accord with the nginx conf