Feature: mDNS service filter.

[dzatoah]

In order to be able to use mdns-reflector in our schools (or Debian Edu),
we need some kind of mDNS service filter, so that only the services
that we want are announced. For example printer (ipp) services.

I will provide patches for this and ideally we find a solution that pleases us both and they can be merged into this Repo.

[sunweaver]

@vfreex Do you see any blockers for implementing this? (Though this would be low prio on our end).

[dzatoah]

Maybe we could use smth like this: https://github.com/mjansson/mdns