Format timestamp.

lms/templates/folditbasic.html

+<%!
+from xmodule.util.date_utils import get_time_struct_display
+%>
 <div class="folditbasic">
 <p><strong>Due:</strong> ${due}
 
@@ -20,7 +23,7 @@
   % for puzzle in completed:
   <tr>
     <td>${'{0}-{1}'.format(puzzle['set'], puzzle['subset'])}</td>
-    <td>${puzzle['created'].strftime('%Y-%m-%d %H:%M')}</td>
+    <td>${get_time_struct_display(puzzle['created'], '%Y-%m-%d %H:%M')}</td>
   </tr>
   % endfor
 </table>