Fall back to the copy of unittest.skipIf that comes with Django if the built-in one isn't available.
Fall back to the copy of unittest.skipIf that comes with Django if the built-in one isn't available.

Signed-off-by: Andrew Pendleton <348b9e0418673058c7539be45a5f1f41a3602290@sunlightfoundation.com>

murphyke/avocado,murphyke/avocado,murphyke/avocado,murphyke/avocado