Fix spelling in build_configs.py

@Kyle-B tracked these down
Support --comm=none,gasnet style cli options.

Thanks to @Kyle-B for original implementation
Move todos out of docstring.
Improve help output.
Include build_configs.py in release tarball.

Maybe the script should go in util/ ?
typo
Move build_configs.py to util/ dir.
Merge pull request #396 from thomasvandoren/build-configs-fixup

Build configs updates.

Updates to `build_configs.py` based on Kyle's review feedback.

Open question: Should `build_configs.py` be placed in util/ dir? My vote is yes. It feels like a more natural spot, especially when included in the release tarball.