title: Cannot match any routes. URL Segment: '': When trying to use child routes and Ng2
body: <p>I have <a href="https://plnkr.co/edit/PHaGNtfa0fPBgET4NEpZ?p=preview" rel="nofollow noreferrer">the following plunker</a>, which does not work. In order to get it to work I can comment out...</p>
  
  <pre><code>RouterModule.forRoot([
        {
            path: "",
            component: TestComponent,
            children: [
                // {
                //    path:"",
                //    outlet: "other",
                //    component: TestComponent
                // }
            ]
        }
  ])
  </code></pre>
  
  <p>If I don't do that I get...</p>
  
  <pre><code>EXCEPTION: Uncaught (in promise): Error: Cannot match any routes. URL Segment: ''
  Error: Cannot match any routes. URL Segment: ''
  </code></pre>
  
  <p>How do I add a child route?</p>