Remove unleash dependency

[boennemann]

Pre-Submission Checklist

• Closes unleash should be moved from dependencies to devDependencies #1521
• Ran the linter and tests via make prepush
• Included comprehensive and convincing tests for changes

Changes

With the release of 6.2.0 (09066d8) the unleash package got added as a dependency of this project. I suppose this happened accidentally, as it's not a real runtime dependency of this project.

Aside from downloading unnecessary bytes this has a very unfortunate consequence.
With the unleash package both "npm-check" and "npm" end up in the users node_modules/.bin folder.

Now if you run npx inside a project that uses restify, or npx npm-check -u for that matter, you end up with unleash's outdated npm-check version, and even worse with an npm@2.

This lead to verify confusing and seemingly unrelated error messages – until I could track it down to this slip-up in restify.

I hope my changes are in the right format, so you can merge this PR directly and release a new version.

I also removed lodash from devDependencies, because it's a dependency already. This gets rid of an npm warning.

Thanks a lot!

[EvgenyOrekhov]

I would call this a fix because unleash and npm@2 broke all my apps. See more info here: npm/npm#18874.

[retrohacker]

Hey all! Sorry for this, looks like npm's new "default to --save" behavior caught one of our contributors by surprise. Thank you for catching this and filing an issue so quickly @boennemann! ❤️ sorry we broke your builds!

Also looks like we failed to semver bump our npm-shrinkwrap file, thank you for doing this in this PR.

[boennemann]

@EvgenyOrekhov You're right. Updated the commit message.

@retrohacker Don't worry, mistakes happen :) In order to keep them from happening again I added another commit. It changes the unleash instructions to use npx. That way nobody has to install unleash explicitly.

[retrohacker]

TIL: npx is a thing! That is awesome!

[boennemann]

🎉