provenance list is now properly sorted

smash/web/templates/provenance/list.html

 {% extends "_base.html" %}
 {% load static %}
+{% load filters %}
 
 {% block styles %}
     {{ block.super }}
@@ -36,7 +37,7 @@
                 <tr>
                     <td>{{ provenance.modified_table }}</td>
                     <td>{{ provenance.modified_table_id }}</td>
-                    <td>{{ provenance.modification_date }}</td>
+                    <td data-sort="{{ provenance.modification_date | timestamp }}">{{ provenance.modification_date }}</td>
                     <td>{{ provenance.modification_author }}</td>
                     <td>{{ provenance.modified_field }}</td>
                     <td>{{ provenance.previous_value }}</td>