title: Ionic 2 datetime component doesn't trigger change event when setting default value
body: <p>I m using Ionic datetime component in my ionic app</p>
  
  <pre><code>    &lt;ion-datetime 
          displayFormat="YYYY/MM/DD" 
          pickerFormat="YYYY MMMM DD" [(ngModel)]="summaryDate" 
         (ionChange)="getDashboardItemsByDate()"&gt;
     &lt;/ion-datetime&gt;
  </code></pre>
  
  <p>and in <code>.ts file</code> I set default date to current date like this</p>
  
  <pre><code> public summaryDate: any = new Date().toISOString();
  </code></pre>
  
  <p>This works perfectly fine, but however the problem I have is, it invokes <code>ionChange</code> event at the beginning (as I have set default value for this component). I just want to trigger this event when user selects the date not at the beginning when I set its default value.
  Any help?</p>