added support for "updated" metadata in a blog post

source/index.haml

@@ -11,6 +11,7 @@ disqus:
       .meta
         - author = (page.respond_to?(:author) && page.author) ? 'by: ' + page.author + ' |' : ''
         #{author} posted: #{post.date.strftime("%B #{post.date.day.ordinalize}, %Y")}
+        = (page.respond_to?(:updated) && page.updated) ? " | upated: #{page.updated}" : ''
       = preserve rp(post.content)
       - if page.respond_to?(:disqus) && page.disqus
         - if post.data["comments_off"]