title: angular translate doesn't refresh translation in controller when I change language
body: <p>I have problem with changing language in controller. When I choose another language, the value in templates change correct translations but translations in controller are still the same.<br>
  How can I resolve this problem?   </p>
  
  <p>I use <code>useStaticFilesLoader</code>.  </p>
  
  <pre><code>.config(function($translateProvider) {
    $translateProvider.useStaticFilesLoader({
      prefix: 'lang/',
      suffix: '.json'
    });
  
  $translate(['safemode_title','safemode_message','server_error']).then(function (translations) {
    $scope.safemode_title = translations.safemode_title;
    $scope.safemode_message = translations.safemode_message;
    $scope.serverError = translations.server_error;
  });
  </code></pre>