a bunch of little optimizations to geocoding

seems to take "san jose, san jose" down from 1s to 400-600ms
"san juan san juan" from >500ms to <300ms

open to other suggestions. These queries are hard because they end up making ~200,000 calls, and the list construction/copying is hard. It looks like just making the lists is one of my biggest hotspots left: http://cl.ly/image/0h0S3e1B170c

Auditors: rahul, nsanch, jliszka