This is now a 6 day span, is that correct? I would have thought this was the expected results:
```
enddate = datetime(2013, 7, 21, 12, 30, 45)
datespan_inclusive = DateSpan.since(7, enddate)
self.assertEqual(datespan_inclusive.enddate, datetime(2013, 7, 22, 0, 0, 0))
self.assertEqual(datespan_inclusive.startdate, datetime(2013, 7, 15, 0, 0, 0))
```