(maint) restrict redcarpet gem to <= 2.3.0

Per the tag annotation from the redcarpet 3.0.0 release, 2.3.0 is the last
version compatible with ruby 1.8.7.

https://github.com/vmg/redcarpet/releases/tag/v3.0.0
(doc) Update to point to the new Jira instance

We've moved from Redmine to Jira. Docs need to point to the new
location.
Merge pull request #588 from zaphod42/maint/facter-2/update-references-for-jira

(doc) Update to point to the new Jira instance
Merge pull request #582 from jhoblitt/redcarpet_gem

(maint) restrict redcarpet gem to <= 2.3.0
Merge branch 'stable' into facter-2
Merge branch 'facter-2'

Conflicts:
	Gemfile