Better clean setup.py

Hi  Andy, 
I rebased my repository against your head. 
The merge should be easy now. 
It worth the effort because it makes the building of packages and testing them 
easier. 
The git command you offered is good, but only for those who use the git sources.
If someone uses the package from pypi, he can use the shell commands. 
But "python setup clean" which cleans the stuff is of course much more user friendly. 
Thanks for your work so far, and I hope this time, is the successful pull request. 

Oz