So you guys still want to distribute NUPIC with third-party libraries included in a cache? My repo is already 422MB. :-\

Also, this is missing --ignore-installed from #171, which I think was important on my system to ignore the system-provided numpy, which if used seemed to cause linker problems.

My recommendation would be to remove the pip-cache related stuff (--no-index, --find-links, --index-url), and add --use-mirrors. Also, in my tests --target wasn't needed because --prefix in the --install-option was sufficient. I also could not find any information online about the use of --target with --install-option & --prefix. I found the docs confusing regarding --target, and couldn't tell whether --target was equivalent to --prefix.

An additional exitOnError after the first pip call might be useful to, as it would help isolate the location of a problem should it arise.

CC: @scottpurdy @oxtopus @breznak