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