added wiki-article-list class to article_list macro template

wiki/plugins/macros/templates/wiki/plugins/templatetags/article_list.html

 {% load wiki_macro_tags %}
 <p><a href="{% url wiki:get path=urlpath.path %}">{{ urlpath.article }}</a></p>
-<div> 
+<div class="wiki-article-list"> 
     <ul>
         <li>
             {% for urlpath in urlpath.children.all %}