title: ng2-tag-input 'tag-input' is not a known element Angular 2
body: <p>I am attempting to install ng2-tag-input into my ionic app.</p>
  
  <p>After successfully installing it with npm install, here is my app.component.ts</p>
  
  <pre><code>import {TagInputModule} from 'ng2-tag-input';
  import {BrowserAnimationsModule} from '@angular/platform-browser/animations';
  @NgModule({
      declarations   : [
          MyApp,
      ],
      imports        : [
          CommonModule,
          BrowserModule,
          HttpModule,
          PagesModule,
          TagInputModule,
          BrowserAnimationsModule,
          IonicModule.forRoot(MyApp, {}, {
              // DeepLinker
              // http://blog.ionic.io/deeplinking-in-ionic-apps/
              links: [
                  {component: ProfilePage, name: 'Profile', segment: 'profile/:username'},
                  {component: PhotoCardComponent, name: 'Photo', segment: 'photo/:id'},
                  {component: ChatMessagePage, name: 'Chat', segment: 'chat/:id'},
                  {component: TermsPage, name: 'Terms', segment: 'terms'},
              ]
          })
      ],
      exports        : [
          BrowserModule,
          HttpModule,
          TagInputModule
      ],
  </code></pre>
  
  <p>Then when I run</p>
  
  <pre><code>ionic serve
  </code></pre>
  
  <p>The following issue happens</p>
  
  <pre><code>Error: Uncaught (in promise): Error: Template parse errors:
  'tag-input' is not a known element:
  1. If 'tag-input' is an Angular component, then verify that it is part of this module.
  2. If 'tag-input' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message. ("
                  &lt;/ion-select&gt;
              &lt;/ion-item&gt;
              [ERROR -&gt;]&lt;tag-input [(ngModel)]="items"&gt;&lt;/tag-input&gt;
  </code></pre>
  
  <p>I am not sure what I did wrong. Can anyone help point it out? </p>