title: ionic toggle with ng-true-value doesn't change the model inside the controller
body: <p>When I use Ionic toggle with on-change function, it works fine.</p>
  
  <pre><code>&lt;ion-toggle ng-model="pushNotification.checked"
       ng-change="pushNotificationChange()"&gt;
  </code></pre>
  
  <p>After adding ng-true-value and ng-false-value the model is not changed, or at least not in on-change function. It changes within the view however, showing binded value correctly.</p>
  
  <pre><code>&lt;ion-toggle ng-model="emailNotification"
       ng-true-value="'Subscribed'"
       ng-false-value="'Unubscribed'"
       ng-change="emailNotificationChange()"&gt;
  </code></pre>
  
  <p>In controller:</p>
  
  <pre><code>$scope.pushNotificationChange = function() {
    console.log('Push Notification Change', $scope.pushNotification.checked);
  };
  
  $scope.emailNotificationChange = function() {
    console.log('Email Notification Change', $scope.emailNotification);
  };
  </code></pre>
  
  <p>Here's the code: <a href="https://codepen.io/anon/pen/jqjjZP" rel="nofollow">https://codepen.io/anon/pen/jqjjZP</a></p>
  
  <p>Push Notifications toggle <strong>logs</strong> correctly to the console, while Newsletter toggle always <strong>logs</strong> 'Subscribed'.</p>
  
  <p>Why?</p>