Bug fix and additional feature.

[mjssjmgithub]

I found an problem when issuing subsequent subscribe commands on a PubSub connection already handling incoming messages from Redis . Also, I added the ability to register a ChannelHander to a pipeline. Since Redis subscriptions are bound to the Redis connection it is useful to know if the connection was severed. This means all subscriptions on that connection are gone and messages may have been missed.

[wg]

Hello Matt, thank you for debugging this issue! I'll be shortly pushing a very slightly different fix and releasing a new version that includes it.

I'm wary of making the public lettuce API dependent on netty, so I'll look into other options for notifying interested parties of connection loss. It might be something best added to the RedisPubSubListener interface.