clearer error message when treebeard is not setup

Author: stefanfoulis

cms/utils/setup.py

@@ -10,7 +10,7 @@ def validate_dependencies():
     Check for installed apps, their versions and configuration options
     """
     if not app_is_installed('treebeard'):
-        raise ImproperlyConfigured('django CMS requires django-treebeard.')
+        raise ImproperlyConfigured('django CMS requires django-treebeard. Please install it and add "treebeard" to INSTALLED_APPS.')
 
     if app_is_installed('reversion'):
         from reversion.admin import VersionAdmin