use zxing to scan qr codes

gui/kivy/uix/screens.py

@@ -101,14 +101,10 @@ class MainScreen(Factory.Screen):
 
 class ScreenSend(CScreen):
 
-    def set_qr_data(self, dialog, uri):
+    def set_qr_data(self, uri):
         self.ids.payto_e.text = uri.get('address', '')
         self.ids.message_e.text = uri.get('message', '')
         self.ids.amount_e.text = uri.get('amount', '')
-        #label = uri.get('label')
-        #if label:
-        # TODO: update label, add to contacts    
-
 
 class ScreenReceive(CScreen):
     pass