Only bundlesize is kept back for Node.js 10.x compatibility.

Newer bundlesize versions still don't work with node.js 10.x.

babel has some bugs that we need to be fixed.

Downgrade bundlesize until they make brotli optional since it doesn't work with node.js 10.x yet.

So, babel, qunit/karma-qunit and bundle-size aren't the latest versions.

* update docs path from docs/4.0/ to docs/4.1/

* bump version to 4.1.0

* Update redirects to work for 4.1 docs move

* Update docs version switcher to include latest and link to 4.0 docs

* re-run dist

* Update package-lock.json

* Update docs-navbar.html

Kept back karma-qunit and qunitjs because tests fail.

Also, include it in the `css` npm script since it's instant.