manage.py path issues

Stephen,

The Fusionbox project, django-widgy, ran into path issues when someone added widgy to an existing mezzanine site: https://groups.google.com/a/fusionbox.com/forum/#!topic/widgy/7t8TBTff3UM

These proposed changes seemed to work: tests ran fine, I was able to run a cronjob, and the site seems to work just fine. 

Can you review this request to see what potential issues we would run into?

Here is the test mezzanine site with django-widgy: https://github.com/zmetcalf/mezz-to-widgy

Thank you,

Zach Metcalf