Create 2014-12-18-ruby-2-2-0-rc1-released.md

This is still draft.
> Also, a reduced pause time thanks to the new Incremental Garbage Collector will be helpful for running Rails applications. Recent developments mentioned on the [Rails' blog post](weblog.rubyonrails.org) suggest that Rails 5.0 will take advantage of Incremental GC as well as Symbol GC.