title: Side nav won't open with template reference variable
body: <p>OK. This is stumping me. The <code>md-sidenav</code> is being referenced by <code>#sidenav</code> in the following template.  However it does nothing.</p>
  
  <pre><code>&lt;md-toolbar color="primary"&gt;
       &lt;button type="button" md-button (click)="sidenav.open()"&gt;
        Open sidenav
      &lt;/button&gt;
  &lt;/md-toolbar&gt;
  
  &lt;md-sidenav-container&gt;
    &lt;md-sidenav #sidenav class="example-sidenav"&gt;
      Jolly good!
    &lt;/md-sidenav&gt;
  &lt;/md-sidenav-container&gt;
  </code></pre>
  
  <p><a href="http://plnkr.co/edit/M8cJTqPKwZwz8UP3dod9?p=preview" rel="nofollow noreferrer">http://plnkr.co/edit/M8cJTqPKwZwz8UP3dod9?p=preview</a></p>
  
  <p>Interestingly, placing a second button within the <code>md-sidenav-container</code> makes both work.</p>
  
  <p>The docs say that you should be able to reference a template variable from anywhere in the template.  Any ideas?</p>