Removed $scope.ownAnnotation() function, added $scope.authorize() instead which utilize annotator.plugins.Permissions.authorize.
For that the permission fields should be filled properly.
  -The plugin needs the 'update' and 'delete' fields to be present.
  -But if the update or delete fields is there with an empty list it means that everybody can update or delete it.
  -So the username is put into the 'update' and 'delete' fields.