title: AngularJS - Incorrect order in ng-repeat
body: <p>I have chaps defined in my controller like this:</p>
  
  <pre><code>  $scope.chaps =  [{"id":"1","chap_no":"1","name":"chap 1"},
                    {"id":"2","chap_no":"2","name":"chap 2"},
                    ...
                    {"id":"14","chap_no":"14","name":"chap 14"},
                    {"id":"15","chap_no":"15","name":"chap 15"}];
  </code></pre>
  
  <p>and in the view, I have:</p>
  
  <pre><code>&lt;li ng-repeat="ch in chaps | orderBy:'chap_no'"&gt;{{ch.name}}&lt;/li&gt;
  </code></pre>
  
  <p>but I'm getting the wrong order (10 after 1, 20 after 2, and so on)</p>
  
  <pre><code>chap 1, chap 10, chap 11, chap 12, chap 13, chap 14, chap 15, chap 2, chap 3, ...
  </code></pre>
  
  <p>Here's the plunkr: <a href="http://plnkr.co/edit/Pc84ooB6dp2zoHXeawYn?p=preview">http://plnkr.co/edit/Pc84ooB6dp2zoHXeawYn?p=preview</a></p>
  
  <p>Can anyone tell me what I'm doing wrong here</p>