title: Set href in attribute directive in Angular
body: <p>I'm trying to set up a Bootstrap tab strip with Angular 2.  I have the tabs rendering in an <code>ngFor</code> but I'm getting template errors when I try to put the <code>#</code> infront of the <code>href</code> expression.  So this template compiles but isn't what I want:</p>
  
  <pre><code>&lt;ul class="nav nav-tabs" role="tablist"&gt;
    &lt;li *ngFor="let aType of resourceTypes; let i = index"
        [ngClass]="{'active': i == 0}"
        role="presentation"&gt;
      &lt;a [attr.href]="aType.Name"
         [attr.aria-controls]="aType.Name"
         role="tab"
         data-toggle="tab"&gt;
        {{aType.Name}}
      &lt;/a&gt;
    &lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>What I want to do is <code>[attr.href]="#aType.Name"</code>
  but that blows up.  What is the correct syntax to prepend the <code>#</code> in front of the expression in the attribute directive?</p>