store tag in buffer to have more numbers

Link: https://github.com/GeneAssembly/biosal/issues/175
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
rename mpi transport to mpi1_p2p

Link: https://github.com/GeneAssembly/biosal/issues/586
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>