Add pre-commit hook for license_finder

[rvirani1]

Hi,

We've recently started using the license_finder gem in our project. It would be great to write a pre-commit hook that would run license finder if any package file (Gemfile.lock, yarn.lock, etc) was changed and then stop if license_finder returned a non-zero exit code. I'd be happy to write a hook if others were interested.

[trotzig]

I think this would be a great addition! I'd be happy to review a PR.

I'm assuming you mean this tool: https://github.com/pivotal/LicenseFinder

[rvirani1]

Yes, that's the one. I'll begin working on a PR.