add synchronized to manager as OWLOntologyManager's are not necessarily
threadsafe, so every direct access to the manager in
SesameDataHandlerImpl is now synchronized on the manger itself

there have been some deadlocks in tests that may have been caused by
this
change URI count predicate
add test for new child count parameter on downloadOntologySubset
change uri count predicate in tests
cleanup EditUserRolesResourceImpl
cleanup