Revise and extend basin/pixel lookups

[gassc]

Basin shortcuts in the API only cover ALCOSAN planning basins. These have incorrect pixel lookups for Chartiers Creek or Upper Mon (not sure which is which - error comes from old data)--need to double-check.

We can fix the shortcuts in the API, but could also further extend the properties of the gauge-adjusted radar rainfall grid cells to show association with HUC-level watersheds.

[gassc]

The pixel lookups for basins were fixed a while back. Extending the properties of the grid cells to show watershed and other geospatial associations is still a possibility, but also something could be done on-the-fly with relative ease via TurfJS