title: angularjs sortby for date unix timestamp not working
body: <p>i'm trying to order a json array using angularjs using timestamp, but its not working for somereson</p>
  
  <pre><code>&lt;div ng-repeat="post in posts track by post.id|orderBy:'post_date':reverse" class="list-group-item apost"&gt;
    &lt;h4 class="timeline-title"&gt;{{post.title}}&lt;/h4&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>js</p>
  
  <pre><code>$scope.Posts = [
    {"id":1,"user_id":1,"title":"Welcome to MRI","body":"\u0641\u064a \u062d\u0627\u0644\u0647 \u0627\u064a \u0627\u0633\u062a\u0641\u0627","post_date":1422929860,"fullname":"MZ"},
    {"id":3,"user_id":1,"title":"\u0641\u064a \u062d\u0627\u0644\u0647 \u0636\u0627,","post_date":1422933651,"fullname":"MZ"},
    {"id":24,"user_id":1,"title":"\u0641\u064a \u062d\u0627\u0644\u0647 \u0627\u064a \u0627\u0633\u062a\u0641\u0633\u0627\u0631","body":"\u0628\u0631\u0631","post_date":1425404937,"fullname":"Mz"},
    {"id":29,"user_id":1,"title":"new post","body":"fk shit mf","post_date":1425405333,"fullname":"MZ"}
  ]
  </code></pre>
  
  <p>i want to show newest posts first.</p>
  
  <p>also is it possible to check if the post_date is today in angular template to apply a special class ?</p>