Add REDIS_SSL option

Allow the worker to connect to a Redis instance through SSL (ex: Azure
Redis Cache use SSL only by default)

rq/cli/helpers.py

@@ -36,6 +36,7 @@ def get_redis_from_config(settings):
         port=settings.get('REDIS_PORT', 6379),
         db=settings.get('REDIS_DB', 0),
         password=settings.get('REDIS_PASSWORD', None),
+        ssl=settings.get('REDIS_SSL',False)
     )