Reachability index.
Avoid traverse owl:Thing node in graph.
adding support on neo4j native graphdb
unit test on reachability index
Refactors and cleans up code before merging with master
Reduces class visibility
Removes redundant state field and reduces dependency on ontologies
Adds some unit tests
Adds some unit tests.
Removes println
Refactors saving index.
Traverse inList and outList in parallel.
Bug fix: one branch of the in-out list traversal was not removed after
adding the parallel implementation.

Fixed the timing code.
Propogates InterruptedException up.
Throws runtime exception in canReach() when start or end node is a
forbidden node.

Unit test udated.
Merge branch 'experimental' of https://github.com/SciCrunch/SciGraph.git into experimental
Switches from forbidden nodes to predicate based node exclusion
Merge branch 'experimental' of https://github.com/SciCrunch/SciGraph into experimental
Merges changes and restores test
Fixes visibility issues