Add Red Hat support and basic tests

This pull request adds a support for Red Hat and testing via rspec-puppet.

Here are some highlights:
1. Gemfile and Rakefile to install required gems and run tests easily
2. A more complete `README`, but there is still more that could be done
3. Basic support for installation on Red Hat systems. It should be noted that there is no service on Red Hat because the `stunnel` package doesn't include an init file.