Pull GTFS and OSM directly from arbitrary URLs

[abyrd]

I frequently have to download a huge GTFS feed to my local machine, then re-upload that same file to Analyst via the web interface. There should be an option in the transit data bundle creation part of the web interface to specify a URL, from which transport-analyst will pull down the file directly.

[abyrd]

It would also be nice to be able to specify a URL for the OSM data. I think most of the time this would suit my needs better than uploading local files: I'd just specify a URL for a Metro Extract and the GTFS feed from a transit authority's web site. That also avoids problems with crazy GTFS extents causing huge OSM downloads from VEX.