title: Format returned date in Angular owl-date-time picker
body: <p>From the below, you can see that I'm using the NEW (1.5.1) <code>owl-date-time</code> picker to return a selected value to the input box.  All is well, except that it's returned as M/d/yyyy and I would like it shown to the user as yyyy-MM-dd.</p>
  
  <p>The [attr.value] does it correctly but doesn't alter what is shown on screen (which I'm guessing is overridden by the <code>[(ngModel)]</code> and I can't add the date pipe in to that line without generating an error - Any ideas?</p>
  
  <pre><code>            &lt;input
                id="tx_date"
                type="text"
                class="mt-25"
                [(ngModel)]="tx_date"
                [owlDateTime]="txDate"
                [owlDateTimeTrigger]="txDate"
                [max]="maxDate"
                [placeholder]="'yyyy-mm-dd'"
                [attr.value]="tx_date | date: 'yyyy-MM-dd'"
                [attr.disabled]="isSelected.date ? null : 'disabled'"&gt;
                &lt;owl-date-time
                  pickerType="calendar"
                  #txDate&gt;
                &lt;/owl-date-time&gt;
  </code></pre>