Compatibility fix of merged QoS features
This merge addresses the following issue:
When adding QoS features to models, there were changes made to model-net-mpi-replay.C that changed the program termination behavior of non-QoS runs. The QoS specific termination behavior is now only triggered if the number of QoS levels is greater than 1 (meaning that QoS is enabled). If the number of QoS levels is 1 (meaning it's not enabled), then the program will follow the termination behavior expected from before QoS features were introduced.