Recent update in rspec-puppet removed some of the config interfaces for old puppet versions[1]. This drops usage of these interfaces to resolve the following error in unit tests. ``` An error occurred while loading ./spec/unit/provider/manila_spec.rb. Failure/Error: c.manifest_dir = File.join(fixture_path, 'manifests') NoMethodError: undefined method `manifest_dir='... ``` [1] https://github.com/puppetlabs/rspec-puppet/commit/316d95923cdbab4daf980629cbded351dd61354c Change-Id: I4b91658648c8cef2176264e995366e1ff73ce00b