[SPARK-3167] Handle special driver configs in Windows

This is an effort to bring the Windows scripts up to speed after recent splashing changes in #1845.
I would link to wherever you found this - maybe here?
http://stackoverflow.com/questions/1230669/subprocess-deleting-child-processes-in-windows

Also, this is a bit scary to just issue kill commands (let's hope `proc.pid` is correct!) but it appears to be the best way to do this ATM.