When computing the URL of a resource, we assumed the object's standard

ID was used to represent that resource in the URL. This isn't always the

case, such as for users and groups.
Resources can now set 'urlIDAttr' to a value representing the attribute

that contains the ID used for the URL.

Made use of this in the new RBCommons ports. It fetched the correct URL.
Other API calls work fine.
Unit tests pass.