Parse workflow bundle as RDF

Nice-to-have feature:

Parse a workflow bundle using RDF instead of XML schemas. Optional install based on SCUFL2-18 - and would allow you to write a workflow bundle which don't conform to the XML schemas, but has valid RDF. (ie. the xsi-headers should be missing from the .rdf files).

The difference from SCUFL2-18 is that this would parse the bundle's individual resources like workflowBundle.rdf and workflow/HelloWorld.rdf.

We should not be writing out workflow bundles not confirming to the XML schemas (but you could output pure RDF as a single file - see SCUFL2-8)