Augment geocoder to make sure transit stations are findable

[graue]

Currently if you type 'antioch bart' or 'san mateo caltrain' the respective transit stations do not come up. This is very bad.

In general, station name + BART or station name + Caltrain only works if the OpenStreetMap node for the station happens to have "Caltrain" or "BART" (somewhat redundantly) affixed to it. "redwood city caltrain" sort of works, but the node that comes up is actually a node called "Redwood City Caltrain Parking" that luckily happens to be next to the station.

Maybe Pelias would do this better, or we could fork Photon. But I'm thinking we could also make the latest GTFS dump available to Bikehopper-web-app, and have it use the GTFS data to augment the results in some way. We could special-case words like "BART", "SMART", "Caltrain", and "station", if we don't mind being Bay Area– and English-specific in a way that would require manual changes in other regions and locales, or try to do something clever like prioritize stops served by subway and commuter rail routes.