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/article.html

@@ -4,7 +4,7 @@
         <header> <h2 class="entry-title"><a href="{{ article.url }}" rel="bookmark" title="Permalink to {{ article.title}}">{{ article.title }}</a></h2> </header>
         <footer class="post-info">
                 <abbr class="published" title="{{ article.date.isoformat() }}">
-                        {{ article.date.strftime('%Y-%m-%d %H:%M') }}
+                        {{ article.locale_date }}
                 </abbr>
                 {% if article.author %}
                 <address class="vcard author">