Stamen Tile CDN returns 503

[jlyon1]

Recently the stamen tile CDN has been returning a 503 error intermittently. A new tile server needs to be found.

[kochman]

We have the beginnings of a self-hosted alternative to this at https://github.com/wtg/tileserver. We would need someone to create nicer, RPI-specific styles—but if we need any tiles at all in a worst-case scenario, we've at least got something. It's running at https://tiles.union.rpi.edu and a tile could be grabbed from e.g. https://tiles.union.rpi.edu/osm_tiles/14/4839/6036.png.

I think we'd probably want to close this issue and work on tile-specific issues on that repo over there, but I'll leave that up to @garoller.

It works with a one-line change in the Shuttle Tracker: