CSS and JS Minification and package.json update

[chiho13]

I think the most useful change is the ability for learners to minify main.js file, especially when they want to deploy the app. It reminds them what is good practice by keeping the total size of web app less than ~1.5 MB. It also saves a lot of initial loading time for visitors.

[StephenGrider]

@chiho13 This looks good, 2 comments:

1. I'm down for this addition, but it should take the form of a new task altogether. Right now the build task is a misnomer, build is typically short for build for production, but we're using it to build the dev version of the app.
2. Match formatting with the rest of the gulpfile, eg .pipe( gulp.dest( './' ) ); to .pipe(gulp.dest('./'));

[chiho13]

do you mean the css minification and js uglify should be one task?