Rouge's Redcarpet plugin now has a different API

See for more:
- 18ec938e9c
- https://github.com/jneen/rouge/issues/182

lib/jekyll/converters/markdown/redcarpet_parser.rb

@@ -48,8 +48,8 @@ module Jekyll
           end
 
           protected
-          def rouge_formatter(opts = {})
-            Rouge::Formatters::HTML.new(opts.merge(wrap: false))
+          def rouge_formatter(lexer)
+            Rouge::Formatters::HTML.new(:wrap => false)
           end
         end