Getting data plane IP addresses for ComputeNode in MP/interdomain slices

[anriban]

Loading a manifest RDF for a multipoint/interdomain slice doesn't seem to create the underlying SliceGraph correctly when one does Slice s = Slice.loadManifest(manifest). There are no interfaces (i.e. s.getInterfaces().size() = 0), and hence one can't obtain the data plane IPs. It works fine in the intra-domain case.