Properly handle namespace packages (oslo, dogpile)
Properly handle namespace packages (oslo, dogpile)

Using `site.addsitedir()` handles namespace packages, where the traditional
`sys.path.insert` does not.  Kudos to Chris Meyers for this discovery.

wwitzel3/awx,snahelou/awx,snahelou/awx,snahelou/awx,wwitzel3/awx,wwitzel3/awx,wwitzel3/awx,snahelou/awx