Add tarball jobs.

The tarball job is in the python-jobs job group; any project that
doesn't have python-jobs but does have pypi-jobs needs tarball set
explicitly.

Change-Id: I6852ae23fff5cca5e8ab524fa7dbf91c9ff72a86
Reviewed-on: https://review.openstack.org/19465
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins