Contents cache demo

Issue: 329

Unknown plugin "transform-async-to-generator" for npm linked repositories

Basically the same issue as next.js had: https://github.com/zeit/next.js/issues/84

And the fix was: https://github.com/zeit/next.js/commit/ca161c375f22c71549849595b68f3e43eda94a89

_{This question is available on Nuxt.js community (#c277)}