added beginnings of tree view for categories

templates/children.html

@@ -0,0 +1,7 @@
+<ul>
+    {% for child in children %}
+    <li> <a href="{{ child.get_absolute_url }}">{{ child }}</a></li>
+        {% child.children.count > 0 %}
+        {% children_list child %}
+    {% endfor %}
+</ul>

templates/main.html

@@ -0,0 +1 @@
+{% children_tag parent %}