Translate rmi:// URIs into local URIs
need to be sent to the server, and then have the relative "xxx" turned into the URI that gets used at the server end. Alternatively, the RMI server code should look for a "graph" parameter (ie. rmi://host/server?graph=foo:bar) that will be interpreted at the server end as an absolute URI.
This is dependent on #155 due to the need to have both relative and absolute URIs.