mdns: update and rename package to the umdns

This update includes numerous small fixes for:
1) Interfaces setup
2) Packets parsing
3) Sending replies
Without this there were multiple problems with exchanging information
between (u)mdns and other implementations (including (u)mdns as well).

This also follows project rename to umdns which was required to avoid
confusion with Apple's mdnsd from mDNSResponder project.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>