[tdwg-tag] Audubon Core namespace

Let's settle this. I think http://abnc.tdwg.org works and is easy to associate with Audubon Core. In my opinion: - ac is too short and not evocative - adbc has too much baggage in the U.S. because of the NSF digitization effort http://www.nsf.gov/funding/pgm_summ.jsp?pims_id=503559&org=&from_org... - adbnc is too long, though a close second for me - audc is possible but more evocative of audio than audubon