Adds check mode support for puppet host tasks.
This works by writing the new puppet host manifest under
/var/lib/tripleo-config/check-mode, and diffing it against the existing
version of the manifest.
Puppet is also run with --noop, so that it only reports on what changes
would have been made.
It also uses the check mode hiera configuration at
/etc/puppet/check-mode/hiera.yaml if it exists so that the updated hiera
data is also accounted for when puppet runs with --noop.
Depends-On: Ibe0c2ab79c35f04ce51e7a1ade0e8ff72b430163
Change-Id: I112b63096c8dce05176b0939a7678bec02987294
6d0f16d430