title: ng-change doesn't work on input
body: <p>I'm new to AngularJS and currently struggling with the following problem.</p>
  
  <p>As you can see <a href="http://plnkr.co/edit/SaBsJVZfHsY4dnaNIfXK?p=preview" rel="nofollow">here in my plnkr</a> I can change the value of the <code>$scope.myDate.value</code>.</p>
  
  <p>The problem now is, that I can't work with this scope in a function, when adding <code>ng-change="barFunc()"</code> to the <code>&lt;input&gt;</code>.</p>
  
  <p>How is it possible to work with <code>ng-change</code> or <code>ng-watch</code> here?
  It would be great if someone could make my plnkr work.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
  &lt;html ng-app="demo"&gt;
  &lt;head&gt;
      &lt;link href="//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet"&gt;
      &lt;link href="//rawgithub.com/g00fy-/angular-datepicker/1.0.3/dist/index.css" rel="stylesheet"&gt;
      &lt;style&gt;
        input {margin: 45px 0 15px 0;}
        pre{padding: 15px; text-align: left;}
      &lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;
  &lt;div class="container"&gt;
      &lt;div class="row"&gt;
          &lt;div class="col-md-4"&gt;
              &lt;div ng-controller="foo"&gt;
                  &lt;input type="datetime" class="form-control" date-time ng-model="myDate.value"
                    ng-change="barFunc()" format="yyyy-MM-dd hh:mm:ss" placeholder="Select datetime"&gt;
                  &lt;pre&gt;myDate: {{myDate.value}}&lt;/pre&gt;
                  &lt;pre&gt;myDate + " abc": {{ custom.value }}&lt;/pre&gt;
              &lt;/div&gt;  
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  
  &lt;script src="//ajax.googleapis.com/ajax/libs/jquery/2.0.3/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src="//code.angularjs.org/1.4.8/angular.js"&gt;&lt;/script&gt;
  &lt;script src="//rawgithub.com/g00fy-/angular-datepicker/1.0.3/dist/index.js"&gt;&lt;/script&gt;
  &lt;script&gt;
  angular.module('demo', ['datePicker']).controller('foo',['$scope', function($scope){
      $scope.myDate = {
          value: ''
        };
        
      $scope.barFunc = function() {
        $scope.custom.value = $scope.myDate.value + " abc";
      };
  }]);
  &lt;/script&gt;
  &lt;/body&gt;
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>