create directories for new users

- use new file tasks to create SFTP and mail base directories for users
- use json serializer as default
- remove TaskResult classes that don't provide any significant benefit

gnuviechadmin/gnuviechadmin/settings/base.py

@@ -282,9 +282,9 @@ CELERY_ROUTES = (
     'osusers.tasks.LdapRouter',
     'osusers.tasks.FileRouter',
 )
-CELERY_ACCEPT_CONTENT = ['yaml']
-CELERY_TASK_SERIALIZER = 'yaml'
-CELERY_RESULT_SERIALIZER = 'yaml'
+CELERY_ACCEPT_CONTENT = ['pickle', 'yaml', 'json']
+CELERY_TASK_SERIALIZER = 'json'
+CELERY_RESULT_SERIALIZER = 'json'
 ########## END CELERY CONFIGURATION