Fix deprecation warning
Merge pull request #95 from tribal-tec/master

Fix deprecation warning
added MPI class
updated mpi.h
remove tabs mpi.cpp
remove tabs
Merge branch 'mpi' of https://github.com/carlosduelo/Lunchbox
CR #96: After reviewing, decided to change the instance to a
shared-copyable approach with explicit instantiation. Cleaned up calling
init/exit to make it more friendly with existing MPI applications.