Update the orterun/mpirun manpage. Corresponds to master commits:

open-mpi/ompi@91e9686
open-mpi/ompi@f9d620e

@jsquyres please review
Add following commits from master:

open-mpi/ompi@9529289
open-mpi/ompi@206eade
Merge pull request #36 from rhc54/cmr/update-orterun-manpage

Update the orterun/mpirun manpage. Corresponds to master commits: