Set scrub_data to True by default.

Considering all the outcry in https://github.com/fog/fog/pull/2526, HackerNews and on Twitter, let's just change this to scrub data by default.

People don't always use the optional arguments, but in this case they should. If they want the speed up from not scrubbing data, they can enable (as they have to do in Fog as well now).