make MPI version checks more explicit.
fix string comparison when empty
remove debug printf
whoops, using undefined flag in test
had to remove head to check for error return
change test to succeed only for OpenMPI versions that support non-blocking collectives
change test to succeed for MPICH/MVAPICH versions that support non-blocking collectives and change the command to set processors per node and export environment variables in a way that works with these versions of mpiexec.hydra
Merge pull request #186 from uwsampa/more-specific-mpi-version-checks

More specific mpi version checks