buttonBoxClicked function causes error when ui is not set tu english

[thbaumann]

The buttonBoxClicked-function causes an error when using a ui in a different language than english.
The function checks if the name of the buttons are "Apply" or "Reset" but if the ui of QGIS is not set to english these buttons won't habe a button-text "Apply" or "Reset" as you can see in the following screenshot:

So on the on hand the functions like self.draw() or self.resetText() will just not be called or if the button-text contains special caracters as shown in the screenshot you this will cause an unicode encode error.