title: PrimeNg multiselect, select all items by default
body: <p>I have a multiselect item from PrimeNg. I can select them if I need, but is it possible to have them all selected by default?</p>
  
  <pre><code>&lt;p-multiSelect [options]="userconfig" [(ngModel)]="selectedScopes" optionLabel="name"
      maxSelectedLabels=3 (onChange)="getCheckboxScope($event)" 
      selectedItemsLabel="{0} users selected" defaultLabel="select users..."&gt; 
  &lt;/p-multiSelect&gt;
  </code></pre>