Based on the work in Cinder,
https://blueprints.launchpad.net/cinder/+spec/shared-backend-config
support for Cinder drivers in the DEFAULT section will be elimiated,
this fix starts a similar change for the puppet cinder module.
Change-Id: Iea1ebb5726ff4e3bf28e11f2f443b7198b4e36bc
Implements: blueprint remove-drivers-in-default