live2dev: Update to npm 5.8.0

In order to fixup https://github.com/cotech/website/issues/98, I had to upgrade npm.

This in turn has updated our lock file. The deployment will need to match versions to work correctly.

(.venv) ➜  website (fixup-gulp-assets) ✔ docker run -it website_assets bash
root@8acf578eb4e7:/# npm --version
5.8.0