Attempt to make config loading syncronous in AngularJS

envConfig.provider.js

(function() {
    'use strict';

    var envconfig = angular.module('app.envConfig', []);
    envconfig.config(confFunc);
    envconfig.provider('startup', startupFactory);

    confFunc.$inject = ['startupProvider'];
    /* @ngInject */
    function confFunc(startupProvider) {
    }

    startupFactory.$inject = [];
    /* @ngInject */
    function startupFactory() {
        var obj = {
            url: 'config/dev.config.js'
        };
        var usingHTTP = ['$http', function($http) {
            $http.get(obj.url).success(function(data) {
                obj = data;
            });
            return obj;
        }];
        function usingXHR(cb) {
            var xhr = new XMLHttpRequest();
            xhr.onreadystatechange = function (resp) {
                if (xhr.readyState !== 4) {
                    return;
                }
                obj = angular.fromJson(xhr.responseText);
            };
            xhr.open('GET', obj.url, false);
            xhr.send();
            return obj;
        }
        function usingAJAX() {
            var xhr = jQuery.ajax({
                type: 'GET', url: obj.url, cache: false, async: false, contentType: 'application/json', dataType: 'json'
            });
            if (xhr.status === 200) {
                angular.extend(obj, angular.fromJson(xhr.responseText));
            }
            return obj;
        }
        /*jshint validthis: true */
        this.$get = usingAJAX;
    }
})();