Add ngmin to the optimize process.

Right now we have to right manually the DI array ['$rootScope,' function($rootScope) {... etc

Which is kinda slow and boring to write everytime. Let's just integrate ngmin in the process. There is probably something cool to do with usemin as well so the ngmin task can use the file you specified in the index.html. Right now it is statically set to "all.min.js"