Fix bug where data would not appear in model after import

The import would succeed, but since it happened during a "Future"
concurrent execution the model was never aware of it and the gui
would not update.  Now, the model's reset slot is connected
so it will be triggered when the indexing finishes.

Libs/DICOM/Widgets/ctkDICOMAppWidget.cpp

@@ -450,10 +450,10 @@ void ctkDICOMAppWidget::onImportDirectory(QString directory)
 
     connect(d->DICOMIndexer.data(), SIGNAL(indexingComplete()),
             progress, SLOT(close()));
+    connect(d->DICOMIndexer.data(), SIGNAL(indexingComplete()),
+            &d->DICOMModel, SLOT(reset()));
 
     d->DICOMIndexer->addDirectory(*d->DICOMDatabase,directory,targetDirectory);
-
-    d->DICOMModel.reset();
   }
 }