Add stringex for Chinese slug generation

lib/slug.rb

@@ -1,10 +1,17 @@
 # encoding: utf-8
 
+
 module Slug
 
   def self.for(string)
     slug = string.gsub("'", "").parameterize
     slug.gsub!("_", "-")
+    if ['zh_CN', 'ja', 'ko'].include?(SiteSetting.default_locale)
+      unless defined? Stringex
+        require 'stringex_lite'
+      end
+      slug = string.to_url
+    end
     slug =~ /[^\d]/ ? slug : '' # Reject slugs that only contain numbers, because they would be indistinguishable from id's.
   end