Attempt to fix for retina display

Change-Id: I652774c70075ed7bbf7fa6a1efff05f432a2d33d
diff --git a/src/main.cpp b/src/main.cpp
index 52c720c..ad4dcf0 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -148,6 +148,7 @@
 {
   qRegisterMetaType<ndn::shared_ptr<const ndn::Data> >();
 
+  QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
   QApplication app(argc, argv);
 
   ndn::Ncc controlCenterGui;