tools: update ESLint to v3.8.0

Update ESLint to v3.8.0.

* Installed with `npm install --production` to avoid installing
  unnecessary dev files
* Used `dmn -f clean` to further eliminate unneeded files

PR-URL: https://github.com/nodejs/node/pull/9112


Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>