Synchronised with kayobe at 93170249303bcfe0ee78350c4dbed02bf5895bee,
prior to cutting stable/stein branch.
Change-Id: I3d79a35a1c75aa9357fc5f77f6b82f9bff843b5e
The addition of this setting overrides K-A's default for Keystone's
token driver of UUID, and configures Fernet instead.
Further discussion and backstory to this change is described
[https://storyboard.openstack.org/#!/story/2001779](over here).