Add X-Forwarded-Ssl and X-Forwarded-Proto for better SSL support

Currently it is not possible for an app to detect if it is accessed via HTTP or HTTPS. 
In order to get this working, we added the [quite common](https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Common_non-standard_request_headers) X-Forwarded-Ssl and X-Forwarded-Proto headers to the nginx configuration for the app