added new default parameter to admin.changeEditBar function in order to ...

...call a class with function if needed

This addition makes it possible to call the changeEditBar function and pass a function name which should be called in the controller.
I needed to change this one to not set an empty fnc value. Setting an empty fnc value breaks some functionality. It was caught by our integration - testing system (Jenkins).
https://github.com/OXID-eSales/oxideshop/commit/42e2459e3563f156b4d39664a960e73fe784fcfc