Rework plugin to work a bit more cleanly. Add metadata and print blurb at bottom of posts.

_layouts/post.html

@@ -12,4 +12,9 @@ layout: default
     {{ content }}
   </div>
 
+  <div class="post-verify">
+    {% if page.md_file %}
+      The markdown source for this post is available here: <a href="{{page.md_file}}">{{page.md_file}}</a> <br/>
+    {% endif %}
+  </div>
 </article>

_plugins/markdown_and_sign.rb

@@ -1,11 +1,14 @@
+# Adds metadata to the post object for linking to the source page.
+Jekyll::Hooks.register :posts, :pre_render do |post, payload|
+  if post.path =~ /\.md$/
+    post.data['md_file'] = "/#{post.data['category']}/#{post.basename}"
+  end
+end
+
 # Copy all of the source markdown files directly into the destination.
 Jekyll::Hooks.register :site, :post_write do |site|
   dest = site.dest
-  categories = site.config['category_metadata'].each_key do |category|
-    dir = Dir.new("#{site.source}/_posts/#{category}")
-    dir.each do |filename|
-      next unless filename =~ /\.md$/
-      FileUtils.cp("#{dir.path}/#{filename}", "#{dest}/#{category}/")
-    end
+  site.posts.docs.select{|p| p.path =~ /\.md$/}.each do |post|
+    FileUtils.cp(post.path, "#{dest}/#{post.data['category']}/#{post.basename}")
   end
 end

_sass/_custom.scss

@@ -36,3 +36,7 @@
   font-size: $large-font-size;
   padding: 0px 10px;
 }
+
+.post-verify {
+  font-size: $small-font-size;
+}