Note that this version of the demo is strictly written in ES6. The gulpfile.babel.js file requires gulp>=3.9 to run the gulp tasks, as it is written in ES6. To get things working, run npm install gulp && npm install gulp -g to update to a version not lesser than 3.9. There's a gulp transpile task which basically transpiles the ES6 code to ES5.
You can find the original version here.