Add deprecation note for redis_cache module name on the documentation.
Fix memcached behavior settings documentation.
Remove sentinel client from codebase.

Pending move it to separated package.
Remove sentinel client documentation.
Fix code style on django_redis.cache module.
Remove raw_cache deprecated property from backend.
Remove unused warning on herd client.
Add missing whitespace line on dummy client.
Fix code style on hash_ring module.
Add missing import on pool module.
Fix code style on pool module.