moment is not defined Angularjs

I am trying to solve this problem that marks when I go to build grunt ... I am using a librería of bower_components called moment . I'm doing this: var moment; but it does not work I do not know what other method I can define this variable.

This is my app.js code

'use strict';

/**
 * @ngdoc overview
 * @name virtualApp
 * @description
 * # virtualApp
 *
 * Main module of the application.
 */
angular.module('virtualApp', [
    'ngAnimate',
    'ngRoute',
    'ngMaterial',
    'ngMessages',
    'ngMap',
    'angular-carousel',
    'mdRangeSlider',
    'pascalprecht.translate',
    'auth0.lock',
    'angular-storage',
    'angular-jwt',
    'rzModule',
    'material.components.expansionPanels',
    'lr.upload',
    'md.data.table',
    'duScroll',
    'angularSpinner'
]).config(['$routeProvider', '$locationProvider', '$translateProvider', 
'lockProvider', '$mdThemingProvider', '$mdDateLocaleProvider', 'usSpinnerConfigProvider', 
function($routeProvider, $locationProvider, $translateProvider, lockProvider, $mdThemingProvider, 
    $mdDateLocaleProvider, usSpinnerConfigProvider) {


    //var moment;


    moment.locale('es');



    $mdDateLocaleProvider.formatDate = function(date) {
        return date ? moment(date).format('DD/MM/YYYY') : null;
    };

    $mdDateLocaleProvider.parseDate = function(dateString) {
        var m = moment(dateString, 'DD/MM/YYYY', true);
        return m.isValid() ? m.toDate() : new Date(NaN);
    };




}]).run(['$rootScope', 'store', 'jwtHelper', '$route', '$http', 'lock', '$window', function($rootScope, store, jwtHelper, $route, $http, lock, $window) {



}]);