pep8 blank lines fixes

flake8 --select W391,E302,E301,E304

autopep8 can't fix W391 even though it claims it can.
Fixed using a simple custom script.

weboob/tools/application/qt/qt.py

@@ -178,6 +178,7 @@ class QtApplication(QApplication, Application):
             QMessageBox.information(None, self.tr('Update of repositories'),
                                     self.tr('Repositories updated!'), QMessageBox.Ok)
 
+
 class QtMainWindow(QMainWindow):
     def __init__(self, parent=None):
         QMainWindow.__init__(self, parent)