add a Case Manager to the Case Vocabulary

"So an instance  of a Case would just be the ID of a case.  And that Case instance (let's call it Case1), can have Notes and Goals as instances associated with it.  So Project1/Case1/Note1 and Project1/Case1/Goal1 and if I add a CaseManager to the vocabulary, we could have Project1/Case1/CaseManager20/" form 8/22/18 slack chat in #linked-data-shared

cc: @cuent 