Running CmdStan tests with OpenMPI

Does anyone (@wds15, @bgoodri) remember how we got OpenMPI to be able to run the CmdStan interface tests? On the new server I’m getting test failures because OpenMPI is inserting some text into the output, and I can’t remember how we ended up turning that off.

eg

src/test/interface/arguments/argument_configuration_test.cpp:1113: Failure
Value of: actual_line
  Actual: "[[46350,1],0]: A high-performance Open MPI point-to-point messaging module"
Expected: expected_line
Which is: "  sample"

I think I found it: https://github.com/stan-dev/cmdstan/pull/618#issuecomment-399241378