Enable Hiera 5

This commit enables the control repo to use Hiera 5 environment-level
hiera hierarchy. This means adding a hiera.yaml to the repo, and moving
hieradata/ => data/.

We should do this to the control-repo template new customers base off of
because in a Hiera 5 world, the global hiera.yaml should be very minimal
(possibly even ONLY having the console level), and everything else
(nodes, common) belongs in the environment hiera.yaml.

This control-repo template is how people start using Puppet. It should
reflect using our most modern technologies.

hiera.yaml

@@ -0,0 +1,12 @@
+---
+version: 5
+
+defaults:
+  datadir: "data"
+
+hierarchy:
+  - name: 'Yaml backend'
+    data_hash: yaml_data
+    paths:
+      - "nodes/%{trusted.certname}.yaml"
+      - 'common.yaml'