Default to new and empty Page Elements instead of None.

Fixes an issue when we try to acces Page.title in the template.

src/content/context_processors.py

@@ -18,8 +18,8 @@ def content_menus(request):
     :param request: a Django request object
     :return: a dict with the template variables mentioned above
     """
-    current_page = None
-    current_top_page = None
+    current_page = models.Page()
+    current_top_page = models.Page()
     current_path = request.path_info[1:request.path_info.rfind('.')]
 
     # erzeuge das Top-Level Menü