bugfix: add provider for puppet tests

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
improvement: check both nginx.conf and conf.d/... for options

Due to differences in the implementation of Chef and Puppet providers, some options will end up in different files. Adding a provider to make sure both files are covered.

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>