title: Polymer: Delay value changed execution
body: <p>Got a simple Polymer template containing:</p>
  
  <pre><code>&lt;paper-input floatingLabel label="Suche" value="{{search}}" error-message="Invalid input!"&gt;&lt;/paper-input&gt;
  </code></pre>
  
  <p>and JS:</p>
  
  <pre><code>properties : {
      search : {
          type : String,
          notify : true,
          observer : 'searchChanged'
      }
  },
  searchChanged : function() {
      this.$.searchAjax.url = /search/" + this.search;
      this.$.searchAjax.generateRequest();
  }
  </code></pre>
  
  <p>So everytime the value changes the server is queried with a new URL. This works good but I want to delay the request to the server for about 500ms to not search after every input the user makes but after he stopped typing for 500ms.</p>