WHAT: Refactor the PMI support into something more flexible
WHY: We currently support both PMI-1 and PMI-2. However, a number of PMI-2 implementations
(specifically, in several Slurm releases) have bugs in them that cause significant problems.
In addition, we have new PMI implementations coming along that we would also like to support.
The current support in OMPI is spread across multiple locations, each of which must track which
PMI version is to be used. Centralizing the PMI integration allows us to avoid that duplication.
TIMEOUT: June 3rd, after the telecon