Add ng-annotate minification to Gulp build

Currently, we use:

app.controller('mainController', function($scope,$http) {
$scope.message =.....
});

mainController.$inject = ['$scope','$http''];

Both $inject and function order and number of arguments must match exactly or minification will fail. This is very error prone especially on larger projects.

By using ng-annotate, you only need to add the @ngInject to the object/method.

https://github.com/olov/ng-annotate