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 djblets __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.
This doesn't get handled automatically by setuptools because this

script is invoked directly via sys.executable() in BuildMedia().

Successfully built Djblets for Fedora