Refactor RDF production to leverage iterators

Resolves https://www.pivotaltracker.com/story/show/57304426

Migrated RDF generated from namespaces to new iterative modality
Switching to use iterated RDF production for triples derived from node properties, except for root node.
RDF triples from version info now returned from iterating components
Now RDF triples returned from Iterators of Nodes also returned from iteration
Fixity result -sourced RDF triples now coming from iterator machinery
RDF based in JCR hierarchy now being constructed in iterator mode
Factoring our type-safe iterators through Guavas ForwardingIterator
Lazy-ifacting Version-based RDF generation