Burst buffer on emulated cray

If running burst_buffer/cray plugin on emulated Cray (NOT a real
   Cray system with Cray APIs) and the burst buffer state information
   includes information about buffers associated with jobs which
   are either completed or no longer exist (i.e. the burst buffer
   state information is old), then ignore that old state information.
   This might possibly be related to bug 3295 if their configuration
   is bad.