Fix git hooks/gulp on Windows

[jeffposnick]

See #2941

[jeffposnick]

@StephanBijzitter, after looking into this a bit, I think things should work with #2947 merged.

Just to give some info as to how I tested this out, in case my environment differs from yours, I used https://github.com/coreybutler/nvm-windows to install node/npm and made sure they were available in my PATH, so that they worked in Power Shell. Once that was done, I ran npm install -g gulp-cli so that I could run gulp build, gulp test, etc.