So we should also change the extension so that it can take additional params and make client.rb parameter optional:
1. server url
2. organization (may be blank for open source chef)
3. validation client

You would have to specify at least one of server url or client.rb, and if you're using enterprise chef, you must specify 2. I believe #3 can be chosen from some sensible default. If you specify client.rb, 1,2, and 3 above would override anything in it.