title: Use getUserMedia with ionic get only black screen
body: <p>Im testing some media features with ionic and im stuck while trying to set the camera output into a video tag using getUserMedia using this code:</p>
  
  <pre><code>navigator.getUserMedia = navigator.getUserMedia ||
                       navigator.webkitGetUserMedia ||
                       navigator.mozGetUserMedia;
  
  if (navigator.getUserMedia) {
     navigator.getUserMedia({ audio: false, video: { width: 500, height: 500 } },
        function(stream) {
           console.log("Im streaming!!", stream);
           var video = document.querySelector('video');
           console.log("video element", video);
           video.src = window.URL.createObjectURL(stream);
           video.onloadedmetadata = function(e) {
              console.log("stream start");
              video.play();
           };
        },
        function(err) {
           console.log("The following error occurred: " + err.name);
        }
     );
  } else {
     console.log("getUserMedia not supported");
  }
  </code></pre>
  
  <p>this is the html:</p>
  
  <pre><code>    &lt;ion-pane&gt;
        &lt;ion-header-bar class="bar-stable"&gt;
          &lt;h1 class="title"&gt;Ionic Blank Starter&lt;/h1&gt;
        &lt;/ion-header-bar&gt;
        &lt;ion-content&gt;
          &lt;video  id="video" autoplay="autoplay" width="500" height="500"&gt;&lt;/video&gt;
        &lt;/ion-content&gt;
      &lt;/ion-pane&gt;
  </code></pre>
  
  <p>i can actually get only a black screen. Is my approach right or im missing something?</p>