Update redcarpet to 2.3.0
Updated jekyll.gemspec manifest site/news/[index.md][releases/index.md] to reflect reality- [index.html]
Merge pull request #1522 from jaybe-jekyll/master

Updated jekyll.gemspec manifest site/news/[index.md][releases/index.md] ...
Update history to reflect merge of #1522
Update gemspec
Merge pull request #1515 from drewish/redcarpet-2.3

Update redcarpet to 2.3.0
Update history to reflect merge of #1515