in progress SesameManager.getObjectTypeMetadata()
 - pass in Contexts instead of an artifact ID
 - include superclass's properties using SPARQL property paths
updated expected statement counts to match modifications in PODD-Base
PoDDSesameManager
 - overload getCardinalityValue() to accept both PODD class and object
URIs.
 - implement getObjectTypeMetadata()
add PoddArtifactManager.exportObjectMetadata() (not implemented yet)