title: CUSTOM_ELEMENTS_SCHEMA added to NgModule.schemas still showing Error
body: <p>I just upgraded from Angular 2 rc4 to rc6 and having troubles doing so. </p>
  
  <p>I see the following error on my console: </p>
  
  <pre><code>Unhandled Promise rejection: Template parse errors:
  'cl-header' is not a known element:
  1. If 'cl-header' is an Angular component, then verify that it is part of this module.
  2. If 'cl-header' is a Web Component then add "CUSTOM_ELEMENTS_SCHEMA" to the '@NgModule.schema' of this component to suppress this message. ("&lt;main&gt;
      [ERROR -&gt;]&lt;cl-header&gt;Loading Header...&lt;/cl-header&gt;
      &lt;div class="container-fluid"&gt;
        &lt;cl-feedbackcontai"): AppComponent@1:4
  </code></pre>
  
  <p>Here is my Header Component:</p>
  
  <pre><code>import { Component } from '@angular/core';
  import { Router } from '@angular/router';
  
  // own service
  import { AuthenticationService } from '../../../services/authentication/authentication.service.ts';
  
  import '../../../../../public/css/styles.css';
  
  @Component({
    selector: 'cl-header',
    templateUrl: './header.component.html',
    styleUrls: ['./header.component.css']
  })
  export class HeaderComponent { // more code here... }
  </code></pre>
  
  <p>Here is my Header Module: </p>
  
  <pre><code>import { NgModule, CUSTOM_ELEMENTS_SCHEMA }      from '@angular/core';
  import { RouterModule } from '@angular/router';
  import { CommonModule }      from '@angular/common';
  import { FormsModule }      from '@angular/forms';
  
  import { HeaderComponent }  from './../../../components/util_components/header/header.component.ts';
  
  @NgModule({
      declarations: [ HeaderComponent ],
      bootstrap:    [ HeaderComponent ],
      imports: [ RouterModule, CommonModule, FormsModule ],
      schemas: [ CUSTOM_ELEMENTS_SCHEMA ]
  })
  export class HeaderModule { }
  </code></pre>
  
  <p>I created a wrapper module called util module which imports the HeaderModule:</p>
  
  <pre><code>import { NgModule }      from '@angular/core';
  
  import {HeaderModule} from "./header/header.module";
  // ...
  
  @NgModule({
      declarations: [ ],
      bootstrap:    [ ],
      imports: [ HeaderModule]
  })
  export class UtilModule { }
  </code></pre>
  
  <p>Which is finally imported by the AppModule: </p>
  
  <pre><code>import { NgModule }      from '@angular/core';
  
  import { BrowserModule } from '@angular/platform-browser';
  
  import { AppComponent }  from './app.component';
  
  import {UtilModule} from "./modules/util_modules/util.module";
  import {RoutingModule} from "./modules/routing_modules/routing.module";
  
  @NgModule({
      bootstrap: [AppComponent],
      declarations: [AppComponent],
      imports: [BrowserModule, UtilModule, RoutingModule]
  })
  export class AppModule { }
  </code></pre>
  
  <p>To my understanding I am following the instructions of the error message using the SCHEMA to surpress the error. But it seems not to work. 
  What am I doing wrong? 
  (I hope its nothing obvious I just don't see at the moment. Been spending the past 6 hours upgrading to this version...)</p>