Changelog:
Edited the setStat() method, so that certain stats can easily be fetched in one line, if someone needed to do that. The function is also shorter now.
Removed duplicate code from get_page_source() method
Got rid of the variable initializing, instead developed the hasattrChecker() method, which will initialize crucial members(properties) if they're called but have not been initialized yet.
Combined calcWlDif() and processFavChampData() into one method called processStats(), so they don't have to be explicitly called when new sites are added. When adding new features, I won't have to update other methods that used those methods (or that will use those methods in the future).
setAllStats() now requires an argument of a list object, it will then set all the stats based on the strings in the list. This way, one can decide himself, which stats he wants to be set.