Re-add bootstrap import

In the update to Angular 4, the bootstrap import got removed from boot.client.ts, causing the navbar-toggle menu to longer work in the template.  Re-adding so navbar-toggle is functional again.

Author: danobri

templates/AngularSpa/ClientApp/boot-client.ts

@@ -1,5 +1,6 @@
 import 'reflect-metadata';
 import 'zone.js';
+import 'bootstrap';
 import { enableProdMode } from '@angular/core';
 import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
 import { AppModule } from './app/app.module.browser';