mDNS implementation in Core Modules #374

Hello,

it could be a nice idea to implement the mDNS system into each core module. There is a nice library on GitHub (https://github.com/jmdns/jmdns) how to implement it in a short way.

The library is also in the Central Repository.

KR,
BlackRose01

P.S.: Here is a program to test if the mDNS service registration was successful.