title: celery with redis - unix timeout
body: <p>I have an app using celery for async-task and i use redis for its broker and result backend and i set redis to use unix socket. 
  here is my url for celery and broker</p>
  
  <pre><code>brok = 'redis+socket://:ABc@/tmp/redis.sock'
  app = Celery('NTWBT', backend=brok, broker=brok)
  app.conf.update(
      BROKER_URL=brok,
      BROKER_TRANSPORT_OPTIONS={
          "visibility_timeout": 3600
      },
      CELERY_RESULT_BACKEND=brok,
      CELERY_ACCEPT_CONTENT=['pickle', 'json', 'msgpack', 'yaml'],
  )
  </code></pre>
  
  <p>but every time i add a job celery gives me this error</p>
  
  <pre><code>Traceback (most recent call last):
  
  File "/usr/local/lib/python2.7/dist-packages/celery/app/trace.py", line 283, in trace_task
      uuid, retval, SUCCESS, request=task_request,
    File "/usr/local/lib/python2.7/dist-packages/celery/backends/base.py", line 257, in store_result
      request=request, **kwargs)
    File "/usr/local/lib/python2.7/dist-packages/celery/backends/base.py", line 491, in _store_result
      self.set(self.get_key_for_task(task_id), self.encode(meta))
    File "/usr/local/lib/python2.7/dist-packages/celery/backends/redis.py", line 160, in set
      return self.ensure(self._set, (key, value), **retry_policy)
    File "/usr/local/lib/python2.7/dist-packages/celery/backends/redis.py", line 149, in ensure
      **retry_policy
    File "/usr/local/lib/python2.7/dist-packages/kombu/utils/__init__.py", line 246, in retry_over_time
      return fun(*args, **kwargs)
    File "/usr/local/lib/python2.7/dist-packages/celery/backends/redis.py", line 169, in _set
      pipe.execute()
    File "/usr/local/lib/python2.7/dist-packages/redis/client.py", line 2620, in execute
      self.shard_hint)
    File "/usr/local/lib/python2.7/dist-packages/redis/connection.py", line 897, in get_connection
      connection = self.make_connection()
    File "/usr/local/lib/python2.7/dist-packages/redis/connection.py", line 906, in make_connection
      return self.connection_class(**self.connection_kwargs)
  TypeError: __init__() got an unexpected keyword argument 'socket_connect_timeout'
  </code></pre>
  
  <p>which option should i use for celery to donot set timeout for its redis connection?</p>