Issue #967

Fix for issue #967. Instead of `urlListStreamProcessor()` simply taking a Layer it now takes three String arguments. This is the way it used to work but I thought a single Layer would be easier. But there is a case (in the MarvlController) where we need to use it but we don't have a Layer object which I didn't think about.

Also added logging so we can see on the server-side the download URLs that are being hit by the users.