Rough progress for DAG-based RDF generation
too many data property matches
More consistent data property matches

Need to figure out why we have duplicate triples for internal node POMs.
Passing first unit test

Needed to remove extra depicts link in r2rml mapping.
Passes events model test case (without provenance)

Removed extra pom for prerequisiteFor in eventsmodel
Remove modifications so unit tests pass
Removed more debug code so unit tests pass
"Fixed" unit tests again

Also added fix for treeifier when node has already been spilled.
Initial support for models with cross products and nested blank nodes with json.
Lots of refactoring

Started to break out the interface for enabling outputs from the rdf
generation process to be something besides rdf.

Clean up.
Cleanup.  Removed unused code
Added new test case for dag
More correct subject generation for dag
Added CommonParentRowColumnAffinity support
Make sure we skip empty nodes
Cleanup of TemplateTermSetPopulator.  Made reusable TemplateSetPopulatorPlan.
Passes all unit tests for RDF generation using the DAG alone
Added json for menus dag test because it was ignored previously
Merge branch 'development' into rdf_dag
DAG RDF generation now passes new artwork csv tests.