Upgrade chokidar, nuxt

Upgrade chokidar and nuxt in order to upgrade upath (as a side effect) and make the project compatible with Node 11. upath v1.0.2 and earlier are not compatible with Node 10 or greater.

The expected report has to be updated:

• Retire.js now finds new vulnerabilities for handlebars, jquery and others
• because of that, vulnerabilities related to hoek are now by Retire.js instead of Gemnasium; that's because the former has a higher priority, so it wins over Gemnasium when removing the dups
• Gemnasium now finds a new vulnerability for axios (added last week)
• Gemnasium doesn't report any vulnerability for ssri anymore; that's because this dependency has been upgraded to a fix version.

So everything seems legit.