Central server production port

PRODUCTION_PORT setting is the default port used when starting the server.  It doesn't check whether CENTRAL_SERVER is True or not.

Now, default PRODUCTION_PORT = 8008 for distributed servers, 8001 for central servers.  

Note: 8001 instead of 80 for central servers, so that this fits our most common scenario (testing) and since our ACTUAL central server doesn't start using Python.

To test:
* Pull onto a central server test server, then run ./start.sh--see that it starts on port 8001.