title: Angular-Kendo ComboBox placeholder text not working
body: <p>I have a simple angular-kendo ComboBox on a page without an initially selected value.  It should show the <a href="http://docs.telerik.com/kendo-ui/api/web/combobox#configuration-placeholder" rel="noreferrer"><code>placeholder</code></a> text in that case, but instead it's showing <code>? undefined:undefined ?</code></p>
  
  <p><strong>HTML</strong></p>
  
  <pre><code>&lt;select kendo-combo-box ng-model="Project" k-options='projectOptions'&gt;&lt;/select&gt;
  </code></pre>
  
  <p><strong>JS</strong></p>
  
  <pre><code>app.controller('MyCtrl', function($scope) {    
    $scope.projectData = [
      {name: 'Bob', value: 1},
      {name: 'Tom', value: 2}
    ];
  
    $scope.projectOptions = {
      placeholder: "'Select...'",
      dataTextField: 'name',
      dataValueField: 'value',
      dataSource: {
        data: $scope.projectData
      }
    }
  });
  </code></pre>
  
  <p>Here's a <a href="http://plnkr.co/edit/sutK7yOGRjNDmZAA0ckr?p=preview" rel="noreferrer">plunker</a> that shows the problem.  Can anyone spot the cause?</p>
  
  <p>This used to work in an older version of angular-kendo, but it's not working in the current version.</p>