Fix #179 - Added test subdir creation back into setup.py, this was lost ...

...in #153 
@doutriaux1 it would be good for you to take a peek at this when you're back at the desk - as we're trying to finalise 1.0.0 and the wiki which points users to the test script, @gleckler1 and I thought it a good idea to put this back where it was a month ago..