To support additional redis options

[TheWangDaolong]

By making this change, it'll be easier to set redis options such as health_check_interval.

celery.conf.ONCE = {
  'backend': 'celery_once.backends.Redis',
  'settings': {
    'url': 'redis://localhost:6379/0',
    'default_timeout': 60 * 60,
    'blocking': True,
    'blocking_timeout': 30,
    **'options':{
        'health_check_interval':25
    }**
  }