Merge functionality from my repo? Ontology support, multiple KG formats, benchmark support.

[esteinholtz-cloudera]

I'd like to see ontology support for a stronger typing of KG entities, and enabling deeper reasoning (ie semantic web) capabilities. Also benchmarking for comparing results between runs. This is all available in my repo: https://github.com/esteinholtz-cloudera/knowledge-graph-system, so I can suggest a (careful) merge if it is of interest.