new port: sysutils/rubygem-r10k

R10K provides a general purpose toolset for deploying Puppet environments
and modules. It implements the Puppetfile format and provides a native
implementation of Puppet dynamic environments.

WWW: https://github.com/puppetlabs/r10k

Differential Revision: https://reviews.freebsd.org/D2778
Approved by: mat (mentor)