Add documentation for Redis Bayes backend to Redis.pm, moved TinyRedis to Util.pm, updated example config for Redis and changed all TinyRedis references to Util::TinyRedis

git-svn-id: https://svn.apache.org/repos/asf/spamassassin/trunk@1557418 13f79535-47bb-0310-9956-ffa450edef68