Changes about locales and dates.

Add a way to specify the locale in the settings, and the date formating as well.
Fixes #61.

pelican/themes/simple/templates/archives.html

@@ -4,7 +4,7 @@
 
 <dl>
 {% for article in dates %}
-    <dt>{{ article.date.strftime('%Y-%m-%d %H:%M') }}</dt>
+    <dt>{{ article.locale_date }}</dt>
     <dd><a href='{{ article.url }}'>{{ article.title }}</a></dd>
 {% endfor %}
 </dl>