Switch back to using the wikistatus package.

OpenStack just goes 'round and 'round.  In Havana
the notification_driver took an absolute python path, but
now it uses an entry point.

I've updated the wikistatus package (v14.11) to set
up the entry point correctly.

Change-Id: Ia59490e15f360c3a22676100437800c09fd9a0f1