Add test for policy

Change-Id: I233a9897f7c340a8a47c46dd9743ef62f7728593

spec/classes/cloudkitty_policy_spec.rb

@@ -19,6 +19,7 @@ describe 'cloudkitty::policy' do
         :key   => 'context_is_admin',
         :value => 'foo:bar'
       })
+      is_expected.to contain_cloudkitty_config('oslo_policy/policy_file').with_value('/etc/cloudkitty/policy.json')
     end
   end