PersistenceMarshallerImpl should not wrap objects when no user marshaller is configured

Currently the PersistenceMarshallerImpl still tries to wrap values that are not in it's SerializationContext even when protostream is to be used directly for user types. This does not make sense, as it will results in a NPE due to a delegate user marshaller not existing. Instead, if protostream is to be used for delegate types the PersistenceMarshallerImpl should state that java primitive values can be marshalled and no wrapping should be attempted.