Fixes #3859 Rollup remaining ORTE changes to sync v1.7 to trunk

Contains a wide range of CMRs (logged into the svn:mergeinfo property) that include:
  * a rewrite of ORTE's oob/rml subsystems to support async messaging
  * add dynamic allocation support
  * modify singleton support so it no longer immediately spawns an HNP
  * support for MapReduce operations

and a variety of other features that I frankly have forgotten.

This is not undergoing a formal review as it is too large and widespread for that purpose. So we'll let this soak for some time, fixing errors that appear via MTT on various systems.