Make it all work again.

Previous iterations and even a release were all broken. The module works again,
sorry for the interlude.

- Giving up on params and moving to module_data (WIP)
- Change the Package and Service references to the static 'bind' name
- Add a meager amount of test coverage

spec/fixtures/hiera/common.yaml

@@ -0,0 +1,2 @@
+---
+bind::confdir: '_CONFDIR_'

spec/fixtures/hiera/hiera.yaml

@@ -0,0 +1,9 @@
+---
+:hierarchy:
+  - "tests/%{::test_config}"
+  - common
+:backends:
+  - yaml
+  - module_data
+:yaml:
+  :datadir: 'spec/fixtures/hiera'