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>