Replace Gulp build tool by NPM

see : 
http://blog.keithcirkel.co.uk/why-we-should-stop-using-grunt/

and then : 
http://blog.keithcirkel.co.uk/how-to-use-npm-as-a-build-tool/

i do the same as gulp with 10 line of npm script...better like this :) read the post above if you have some time ! very interesting !!