rescue block for the method and added redcarpet as option for parser

lib/jekyll/converters/markdown.rb

@@ -19,7 +19,7 @@ module Jekyll
             MarukuParser.new @config
           else
             STDERR.puts "Invalid Markdown processor: #{@config['markdown']}"
-            STDERR.puts "  Valid options are [ maruku | rdiscount | kramdown ]"
+            STDERR.puts "  Valid options are [ maruku | rdiscount | kramdown | redcarpet ]"
             raise FatalException.new("Invalid Markdown process: #{@config['markdown']}")
         end
         @setup = true

lib/jekyll/converters/parsers/redcarpet_parser.rb

@@ -3,7 +3,6 @@ module Jekyll
     class Markdown
       class RedcarpetParser
         def initialize(config)
-          begin
           require 'redcarpet'
           @config = config
           @redcarpet_extensions = {}
@@ -28,7 +27,6 @@ module Jekyll
           STDERR.puts '  $ [sudo] gem install redcarpet'
           raise FatalException.new("Missing dependency: redcarpet")
         end
-        end
 
         def convert(content)
           @redcarpet_extensions[:fenced_code_blocks] = !@redcarpet_extensions[:no_fenced_code_blocks]