Fix puppetmaster dependencies

This PR is part of getting the [puppet-puppet](https://github.com/puppetlabs-operations/puppet-puppet) module ready for a new release.

The init script change is necssary because running a unicorn puppetmaster as a non-root user currently fails because the puppetmaster tries to access $HOME/.facter/facts.d, but the current init script provided by this module doesn't provide one. The logs then fill up with messages like `Could not initialize global default settings: couldn't find HOME environment`.

The other change is adding the [rack](https://github.com/puppetlabs-operations/puppet-rack) module to the Modulefile.