Introducing Puppet Module Data

This PR is an incremental step to introduce changes that were proposed in https://github.com/jfryman/puppet-nginx/pull/423.

The scope of this pull is to eliminate the `params.pp` class, and collapse any user-configurable data to Hiera. Instead of attempting to explain _why_, I'll link this wonderful post.

http://www.devco.net/archives/2013/12/08/better-puppet-modules-using-hiera-data.php

I'm not a fan of warning - there is a tendency for those to get lost on a Puppetmaster logs, as opposed to a `notify` that is in-your-face on the client.