add gulp dev tool

[Adel]

@manland @jeremy-flusin @melanie-konig It is still in progress! Only build task was done which does:

• jshint
• sourcemaps
• rollup
• uglify
• minify css
• inject minified css and js into html index file
• watch on html, js, tests and css files
• jasmine tests It seems somewhat complicated, any idea if we can do better? (90 lines instead of 1 line in package.json to build...).

Todo still: add a env variable to set if the sourcemaps comment will be added to the html or not. Added sourcemaps in prod build for debug purposes.

No watches, no tests, no zipping and no checking zip size for now

[manland]

Hahaha welcome in my world ^_^