Add a constant for a default TTL and some debug logging.
Add support for serializing non-QD records.

Extend the BufferWriter to serialize long and buffers.
Turn the packet flags into an enum.
Fix outdated comment -  the timeout is actually 5 secs.
Add api to announce services.

The api is modelled closely after the mdns module. There is a new Advertisment
class that has start() and stop() methods. The function has been verified with
'avahi-browse -a' and wireshark.
Add me to the contributors file.
Only add '.local' to address if not already present.