Use absolute import work around Django 1.3 bug.

The tests for Django 1.3 are failing using the relative import
(introduced in commit da53b574a4), because Django does this janky
thing where it django.core.management assumes your settings
are at the root of your project package, and imports that
package. Problem is, once a sub-package, such as gcframe.tests
is imported as a package (tests) Python will no longer let you
do a relative import beyond that new root. An absolute import
avoids that issue.