Added diff test. Implementation of diff for Sesame. Plantain fails.
fix plantain diff, so it deals with NoSuchElementExceptions ( and other problems ). Passes tests.
scalariform
forgot tests

Conflicts:
	rdf-test-suite/src/main/scala/GraphTest.scala
	rdf-test-suite/src/main/scala/RDFOpsTest.scala
Merge pull request #107 from read-write-web/plantainFix

Plantain fix diff implementation #106