Rewrite check_redis to use hiredis library.
Create libredisutils with a redisCommand wrapper.
Addapt to hiredis and libredisutils.
Add falback if hiredis has no pkg-config file.
Add check_redis_slave check.
Add doc for check_redis_slave and update check_redis.
Remove old check_redis.
Addapt packages to redis rework.
Add missing file
Merge branch 'hiredis'