Nginx support for http local reverse proxy (i.e. TLS reverse higher up the chain)

Addressing part of #6 (closed).

Here we add key and modify nginx templates (compression settings becomes an option) to handle both Nginx as a TLS reverse proxy (default and current behaviour) or as a local HTTP Web server tapping into funkwhale server.

This new option, when enabled, also removes some of the proxy settings, which were counter-productive on my own implementation, resulting in mixed HTTP/HTTPS content.