CORBA23 — UNIQUE_ID and ServantActivator issue

Summary: What should happen if the servant returned from a
ServantActivator::incarnate call is already registered for another
object id, and the POA has the UNIQUE_ID policy?

Since this is clearly an error, I suggest raising the OBJ_ADAPTER
exception (which will be returned to the client whose request prompted
the call to incarnate). I also suggest requiring the POA to call
ServantActivator::etherealize for that object id. The latter is
necessary to allow the application to dispose of any resources
associated with that object, and to ensure that an application will
never recieve two calls to ServantActivator::incarnate for a particular
object id without an intervening call to ServantActivator::etherealize.

Incorporate change and close issue