Fix for "Who's Using" links

Liquid was not properly iterating through the using_hash.
Needed to add a second for loop.

See: http://stackoverflow.com/questions/8206869/iterate-over-hashes-in-liquid-templates

_includes/sidebar.html

@@ -35,7 +35,9 @@
       <h3>Who's using this license?</h3>
       <ul>
         {% for using_hash in page.using %}
-          <li><a href="{{ using_hash[1] }}">{{ using_hash[0] }}</a></li>
+          {% for using in using_hash %}
+            <li><a href="{{ using[1] }}">{{ using[0] }}</a></li>
+          {% endfor %}
         {% endfor %}
       </ul>
     </div>