new port: textproc/rubygem-creole

Creole-to-HTML converter implemented in Ruby for Creole,
a lightweight markup language.

WWW: http://github.com/minad/creole

PR: 199816
Differential Revision: https://reviews.freebsd.org/D2486
Submitted by: Torsten Zuehlsdorff <ports@toco-domains.de>
Approved by: mat (mentor)