Merge pull request #234 from thewacokid/master

Rewrite of plfsrc.example, updated README.install, and added a 1.7.x patch for openmpi
Update process for generating a prep.patch to be more clear.
Merge pull request #235 from dshrader/master

Update the process for generating a new prep.patch.
Merge pull request #236 from thewacokid/master

Better errors with bad plfsrc
Updated patch for ompi-1.7.x