BUG: ctkDICOMBrowser: Fix ImportDirectories test

This commit fixes issue with ctkDICOMDatabase::instancesForSeries identified
in previous commit.

Libs/DICOM/Core/ctkDICOMDatabase.cpp

@@ -745,7 +745,7 @@ QStringList ctkDICOMDatabase::instancesForSeries(const QString seriesUID)
   query.bindValue(0, seriesUID);
   query.exec();
   QStringList result;
-  if (query.next())
+  while (query.next())
   {
     result << query.value(0).toString();
   }