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_views.py

@@ -1,4 +1,5 @@
 from decimal import Decimal
+from unittest.mock import patch
 
 from django.test import TestCase, Client
 from django.contrib.auth.models import User
@@ -46,8 +47,9 @@ class AccountTests(TestCase):
             amount=Decimal('3')
         )
 
-    def test_account_read(self):
-        """We can query the  "Accout - Read" page."""
+    @patch('gestioncof.signals.messages')
+    def test_account_read(self, mock_messages):
+        """We can query the  "Account - Read" page."""
         client = Client()
         self.assertTrue(client.login(
             username="foobar",