Switch to Yarn

[pvhee]

• Use Yarn as our package manager
• Wrap gulp tasks into yarn scripts and document. You'd build the site using yarn build rather than gulp build

[Quicksaver]

@pvhee to clarify, is the goal also to get rid of anything-gulp and use node scripts to feed yarn instead?

I.e. get rid of gulpfile.js and yarn start would call something like node start.js, etc.

[Quicksaver]

Personally, I'd stay with gulp tasks at least for now. Rewritting them into node scripts / CL commands could be fun (at least from a learning point of view), but from what I'm seeing they would hardly save on dependencies and would take a lot more lines of code than we have now with gulp.