title: Ionic2: Input field, Why Im getting empty string in value
body: <p>This is my client side :</p>
  
  <pre><code>&lt;ion-card *ngFor="#p of posts | async"&gt;
      &lt;ion-card-header&gt;
          {{p.title}}
      &lt;/ion-card-header&gt;
  
      &lt;ion-card-content&gt;
          &lt;form [ngFormModel] = 'form' (ngSubmit) = 'addcomment(form.value, p.$key)'&gt;
              &lt;ion-input  type="text" placeholder="your comment" (ngModel) = 'comment'&gt;&lt;/ion-input&gt;
              &lt;button&gt;add comment&lt;/button&gt;
          &lt;/form&gt;
      &lt;/ion-card-content&gt;
  &lt;/ion-card&gt;
  </code></pre>
  
  <p>And in .ts :</p>
  
  <pre><code>this.form = fb.group({
      'comment': ['', Validators.required]
  });
  this.comment = this.form.controls['comment']
  </code></pre>
  
  <p>If i print in the console the <code>form.value</code> inside <code>addcomment()</code></p>
  
  <pre><code>Control {asyncValidator: null, _pristine: true, _touched: false, _value: "", _errors: Object…}
  </code></pre>
  
  <p>and <code>this.comment</code> (<code>AbstractControl</code> type of variable inside class) is empty.</p>