new resource model

This is a revised resource model diagram.

I have removed the confusing service model aspect of discovery, and 
added in agents using discovery services to discover resources. It does 
not seem to be necessary to add publishing, but I am open to that.

I have added in that resources may have representations. I realize that 
services may not have useful representations, but other resources do.

I have also tied in a resource's URI to the resource description: i.e., 
its not a description of the resource if it does not identify it. This 
is potentially controversial - it disallows descriptions of the form: 
all resources which are colored red.

A person who owns a resource also set policy on it. That policy may be 
linked to from the description. Again, there may be others who *also* 
set policies on resources (the hosting agency for example).

Let me know comments. Failing a negative response, I will draft text 
that fleshes this out.

Frank