selecting urlconf conditionally; remove obsolete urls.py

This is cleanup to address #258.  Title says it all.  I tested on both main and central servers.

To validate:
* Pull the code and run on a central and distributed server.

From Wednesday's testing training, anybody should be able to test this out.  @wangguan59 this would be a good way to confirm that you've got central and distributed server setups working, and that you can manage pull requests.  @aronasorman This might be a good one for you as well.