Fix Crash if Krita's online version String is empty in offline sessions

Krita will crash if there is no internet connection as online Version String will return empty. This patch ensures that crash does not happen and also enhances the code to be a little more robust on version checking and errors. Converts version lists to integers before comparing and makes the lists have the same lenght

Development git versions does not check for updates.

Also made the code follow the hacking style much closely