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/tests/test_statistic.py

@@ -9,7 +9,8 @@ from kfet.models import Account, Article, ArticleCategory
 
 
 class TestStats(TestCase):
-    @patch('kfet.signals.messages')
+
+    @patch('gestioncof.signals.messages')
     def test_user_stats(self, mock_messages):
         """
         Checks that we can get the stat-related pages without any problem.