simplify + fix lots of things about geocoder.html

1) use history.pushState, and stop using fragments, which were annoying
2) respect maxInterpretations in the url
3) have an ll and a query box
4) submit-on-enter
5) rely on request geom from the server
6) deprecate a few dumb params that we were just rewriting to other param names
7) some minor visual tweaks

makes the logic ever so slightly cleaner. would be awesome to use the thrift-js here, but I don't think that's happening anytime soon.

Auditors: rahul