Test DNS-SD implementation

[farshidtz]

Similar to Fujitsu's sequence diagram (b): https://github.com/w3c/wot-discovery/tree/master/prior-work/fujitsu

[farshidtz]

info about the latest implementation: https://github.com/linksmart/thing-directory/wiki/Discovery-with-DNS-SD

[blubbfish]

Looks good, dns-sd was found over lan in a class b network.

Write a program to:

• Browse for service instance using type
• Browse for service instance using subtype
• Resolve/lookup the instance and get port, hostname, txt records
• Add a TD

[farshidtz]

FYI, ea5f394. The config is changed to "interfaces" with an array of strings as value.

[blubbfish]

Sample Implementation: https://github.com/blubbfish/dns-sd-tester