Improvements for K-Fêt CMS.

K-Fêt - Wagtail
- Page content becomes a StreamField.
- GroupTeam snippet becomes a block for stream field.
- Navigation menu moved becomes a "flatmenu", preventing possible future conflicts.
- Page layout can be modified in wagtail admin.

K-Fêt
- Add shorthands for ukf account balance/article price.
- Cleaning stylesheets and templates.

kfet/cms/hooks.py

@@ -0,0 +1,12 @@
+from django.contrib.staticfiles.templatetags.staticfiles import static
+from django.utils.html import format_html
+
+from wagtail.wagtailcore import hooks
+
+
+@hooks.register('insert_editor_css')
+def editor_css():
+    return format_html(
+        '<link rel="stylesheet" href="{}">',
+        static('kfetcms/css/editor.css'),
+    )