Keith is going to try to use Zulip again during the next conference;
CoNEXT, so we need to rebrand. We use generic language here so that
we don't need to do this every time.
(imported from commit c97f7d4bb84f2dfd4c6db265884ba17be0fd5677)
This needs to be deployed to both staging and prod at the same
off-peak time (and the schema migration run).
At the time it is deployed, we need to make a few changes directly in
the database:
(1) UPDATE django_content_type set app_label='zerver' where app_label='zephyr';
(2) UPDATE south_migrationhistory set app_name='zerver' where app_name='zephyr';
(imported from commit eb3fd719571740189514ef0b884738cb30df1320)