"http://" and port number forced on feed xml addresses about podsync

[mxpv]

That's the opposite to #43
Probably port and hostname should be independent.
So it'd be possible to cover both cases:

port=8080
hostname=http://myserver:8080

and for cases with frontend

port=8080
hostname=https://myserver.net (nginx redirects to `http://localhost:8080`)

It might also make sense to embed https functionality (for instance with automatic Let's encrypt).

[bartlibert]

This seems a good solution. Maybe make the builtin Let's encrypt support optional, as it might interfere with nginx encryption (not sure?)?

[mxpv]

@bartlibert for sure, it must be optional