title: ng-selected not working in md-select
body: <p>I am new bee to angular2 and I have been unable to write code for a dropdown, to be precise I have written all its code everything is working but I am having problem in showing the default value of the </p>
  
  <pre><code>&lt;md-select ngModel="selected-preset"&gt;
    &lt;md-option *ngFor="let preset of getAllPresets()" ngSelected="preset == getPreset() ? true : null"&gt;{{preset | translate}}&lt;/md-option&gt;
  &lt;/md-select&gt;
  </code></pre>
  
  <p>presets gives me a dropdown showing 4 values and one of these values is same as getPreset() function, but still it is not selecting that value by default.</p>
  
  <p>Any help would be appreciated.</p>