feat: new Web UI build system

- use generator-gulp-angular by @swiip
- remove old static file

static/app/sections/providers/providers.module.js

@@ -1,21 +0,0 @@
-(function () {
-  'use strict';
-
-  angular
-    .module('traefik.section.providers', [
-      'traefik.core.provider',
-      'traefik.section.providers.backend-monitor',
-      'traefik.section.providers.frontend-monitor'
-    ])
-    .config(['$stateProvider', function ($stateProvider) {
-
-      $stateProvider.state('provider', {
-        url: '/',
-        templateUrl: 'app/sections/providers/providers.html',
-        controller: 'ProvidersController',
-        controllerAs: 'providersCtrl'
-      });
-
-    }]);
-
-})();