Fix permission name for creating repositories.

The Repository API already had some plumbing to allow users with a given
permission to create repositories regardless of their admin/staff status, but
it was using the wrong permission name. Trivial change.

Testing done: Ran unit tests.

Fixes bug 3307.
Support building media with parallel-installed Django

On systems such as Fedora where older versions of Django are installed as
alternative versions (and not directly importable), we need to ensure that we
are importing exactly the right version of the Django modules.

This patch adds a new variable in the reviewboard __init__.py that is imported
by both setup.py and build-media.py to ensure that they are both relying on the
same version of Django.

Testing Done:
Built successfully on Fedora.

Reviewed at https://reviews.reviewboard.org/r/5690/