Adding configure options for GPU aware MPI.
Implementing GPU aware MPI messaging.
Merge branch 'master' into gpu-aware-mpi
Merge branch 'master' into gpu-aware-mpi
Added missing include of config.h
Fixing various includes.

No idea why these used to compile.
Merge branch 'master' into gpu-aware-mpi
Getting rid of an unnecessary data host-device.
Merge remote branch 'origin/gpu-aware-mpi' into gpu-aware-mpi
Merge branch 'gpu-aware-mpi'