Document correct way(s) to deploy over HTTPS

[Habbie]

Notes:

• gunicorn can apparently do SSL itself

• when putting non-SSL gunicorn behind Apache mod_proxy, this works:

  ProxyPass / http://127.0.0.1:5000/ RequestHeader set X-FORWARDED-PROTOCOL ssl RequestHeader set X-FORWARDED-SSL on

• nginx most likely can do something simple that makes sense

[zeha]

Relevant info:

• https://github.com/benoitc/gunicorn/blob/97977e41ab87ab7725ca157c689c9ca87bf502d6/docs/source/settings.rst#secure_scheme_headers
• http://flask.pocoo.org/docs/deploying/wsgi-standalone/#deploying-proxy-setups
• werkzeug.contrib.fixers ProxyFix