fix path for tray icon (issue #263)

gui/gui_classic/main_window.py

@@ -163,7 +163,7 @@ class ElectrumWindow(QMainWindow):
         self.lite = None
         self.current_account = self.config.get("current_account", None)
 
-        self.icon = QIcon(os.getcwd() + '/icons/electrum.png')
+        self.icon = QIcon(':icons/electrum.png')
         self.tray = QSystemTrayIcon(self.icon, self)
         self.tray.setToolTip('Electrum')
         self.tray.activated.connect(self.tray_activated)