Add support for redis name override used in RedisURL

[devilleweppenaar]

Currently we use the default value for the RedisURL set to:

  config:
    # redisURL sets the Redis connection URL
    redisURL: "redis://{{ .Release.Name }}-redis-master:6379"

This works until you specify the nameOverride or fullnameOverride for redis.

See the common.names.fullname template from bitnami/common.