taxonomy: add dnssdmon.

Depending on specific apps installed, iOS devices will
periodically send DNS-SD cache updates which include TXT fields
in the Additional Records containing model information. Watch
for these messages for an extended period of time, half an hour
by default, then print them out and exit. It is expected to be
run in a loop in this way.

Apple uses several different model numbering schemes in these
announcements: https://www.theiphonewiki.com/wiki/Category:Devices
Provide a hash table to map from these identifiers back to a
meaningful model name.

Change-Id: I167dd2b051ab8f3e80923cfe543bd83ddad90958
6 files changed