Make test suite compliant with PostGIS

[andrewbt]

This is just notes of the issues I saw for now, I will clean this up later / split into separate issues:

http://postgis.net/docs/ST_NPoints.html (wrong function)
https://github.com/CityOfPhiladelphia/soda-carto/blob/master/test/index.js#L122

http://postgis.net/docs/ST_Distance.html (cast to geography)
https://github.com/CityOfPhiladelphia/soda-carto/blob/master/test/index.js#L130

https://github.com/CityOfPhiladelphia/soda-carto/blob/master/test/index.js#L143 (could be replaced by the star variable above?)

https://github.com/CityOfPhiladelphia/soda-carto/blob/master/test/index.js#L154 (should this be "location" and not the_geom??)

http://postgis.net/docs/ST_Intersects.html (the WKT needs to be casted to geometry)
https://github.com/CityOfPhiladelphia/soda-carto/blob/master/test/index.js#L274

http://postgis.net/docs/ST_MakeEnvelope.html (need to swap order here, socrata within_box is different ordering of xmin, ymax, xmax, ymin than what postgis expects)
https://github.com/CityOfPhiladelphia/soda-carto/blob/master/test/index.js#L290

http://postgis.net/docs/ST_Within.html (the WKT needs casting to geometry maybe? or use st_geomfromtext?)
https://github.com/CityOfPhiladelphia/soda-carto/blob/master/test/index.js#L306

https://github.com/CityOfPhiladelphia/soda-carto/blob/master/test/index.js#L314 (missing - but you could easily do carto's updated_at maybe?)

https://github.com/CityOfPhiladelphia/soda-carto/blob/master/test/index.js#L394 (missing?)

[andrewbt]

Upon further research, going to need to revise some of these recommendations. Would be better to use the_geom_webmercator and some trigonometry for distance calculations and so on, rather than casting to ::geography. Will allow use of meters units, while also engaging the default geometry index on that column for better performance, while also being the most accurate considering our data is local to a city and not global.

(as described in https://carto.com/blog/nearest-neighbor-joins)

[timwis]

Bugs identified by this issue:

• $select=num_points(location) L122
• $select=distance_in_meters(location, ....) L130
• $where=intersects(location, ....) L274
• $where=within_box() L290
• $where=within_polygon() L306

[timwis]

@andrewbt regarding L306, it looks like it does use GeometryFromText. So are we good on that one?