Merge PRRTE MCA namespace into the OMPI one

[hppritcha]

A follow-on to issue #16. Once PRRTE source code is moved out of 3rd-party to a top level folder, it may be worth seeing what would be involved in flattening the MCA space so that the PRRTE project MCA namespace would be subsumed into the OMPI MCA name space.

One can get an idea of the changes involved by seeing where orte appears in the top level autogen.pl file in the v4.1.x branch of OMPI.

With this done, there would no longer be a need for a separate prte_info executable.