Windows support

These are a few changes to better support Windows.  We may want to add a warning to the documentation that we don't really want to support Windows, but are just including it as is.
I agree with @jeffbaumes .

Also the more I think about it, I am inclined to just not support this feature on windows since it's really not a very important feature. We could replace this hideous code with simply:

    if hasattr(os, 'statvfs'):
        ** do the current behavior **
    else:
        return {
            'free': None,
            'total': None
        }