add thumbnail to /archive.html template.

templates/archive.html

@@ -5,7 +5,11 @@
 
 {% for entry in archive-entries %}
 <div>
-  <a href="/view/archive/{{entry.slug}}">{{entry.title}}</a>
+    <a href="/view/archive/{{entry.slug}}">
+	<img alt="{{entry.title}}"
+	     src="/storage/thumb/archive/{{entry.slug}}">
+      {{entry.title}}
+  </a>
 </div>
 {% endfor %}