title: angular material datepicker doesn't open in modal dialog
body: <p>I have an angular material 2 date-picker implemented in a bootstrap modal form:</p>
  
  <pre><code>&lt;div class="modal-dialog modal-lg"&gt;
    &lt;div class="modal-content"&gt;
      &lt;div class="modal-header"&gt;
        &lt;h4 class="modal-title"&gt;{{title}}&lt;/h4&gt;
      &lt;/div&gt;
      &lt;div class="modal-body"&gt; 
          &lt;div class="timeline-cal"&gt;
              &lt;input class="date-field" [mdDatepicker]="picker" placeholder="Choose a date"&gt;
              &lt;md-datepicker-toggle mdSuffix [for]="picker"&gt;&lt;/md-datepicker-toggle&gt;
              &lt;md-datepicker #picker&gt;&lt;/md-datepicker&gt;
          &lt;/div&gt;
          &lt;div class="modal-footer"&gt;
              &lt;button type="button" class="btn grey-btn pull-right"     (click)="cancel()"&gt;Cancel&lt;/button&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>However, upon clicking the button, the datepicker wouldn't open in the modal dialog itself but opens in the background. I tried this but didn't help:</p>
  
  <pre><code>.mat-datepicker-content{    z-index: 1200}
  </code></pre>