URLs not constructed properly if behind reverse proxy

[schaarj]

Adding some headers to the proxy directive fixes the major issues (e. g. /login or the like redirect to an internal address) but still not all.
SPARQL endpoints remain displayed as:

http://[url]:None/api/v1/jena/tt_test/sparql

even though it should be:

https://[url]/api/v1/jena/tt_test/sparql

(Use https and don't use a port if the reverse proxy is listening on the default 443)