Add nuancier.proxy and set nuancier as an application behind a reverse proxy

This will ensure that flask.redirect is using ``https`` where asked.

Fixes https://fedorahosted.org/fedora-infrastructure/ticket/4369 for nuancier
Adjust the reverse proxy settings
Merge pull request #38 from fedora-infra/fix_https

Add nuancier.proxy and set nuancier as an application behind a reverse p...