Subject geocoding follow-up work

[danvk]

• Geocode all the East River Piers
• Look into the remaining “title” matches
• Fold the IGNORE_SUBJECTS into tasks.csv and remove that variable.
• Rename "nyc-parks" geocoder to something like "poi" or "subjects"
• Look for borough mismatches
• Drop the big lists of locations in subjects.py in favor of subjects.geojson
• Look into subjects/names

The potential upside for remaining subject geocoding is limited, so these might not be worth the effort.