devel/rubygem-que-scheduler: Add rubygem-que-scheduler 4.2.2

que-scheduler is an extension to Que that adds support for scheduling items
using a cron style configuration file. It works by running as a que job itself,
determining what needs to be run, enqueueing those jobs, then enqueueing itself
to check again later.

WWW: https://github.com/hlascelles/que-scheduler