Refactor nrpe to a module

Turned the manifests into a module, added/cleaned up documentation, made
puppet-lint happy, moved/created templates and/or files. Added unit
tests. Also update site.pp/base.pp to not explicitly load nrpe.pp
Still needs some love but this will work for starters. Rspec tests have
also been added, but fail at this point

Change-Id: I64a9f1d60cbabeef3a096981d634d7399d39bc45