Adds "Recovered" log line for successful channel recovery.

This is not a terribly important pull, but definitely a nice-to-have.  
  
In the [ConnectionHandler recovery](https://github.com/jhalterman/lyra/blob/master/src/main/java/net/jodah/lyra/internal/ConnectionHandler.java#L218), after a channel is successfully recovered there is a log line to state it was recovered. This log has great utility in confirming that the connection was recovered, however the [ChannelHander recovery](https://github.com/jhalterman/lyra/blob/master/src/main/java/net/jodah/lyra/internal/ChannelHandler.java#L211) does not have a similar line.
  
This change will take this log snippet: 

    20:00:54 ERROR [AMQP Connection 192.168.0.200:5000] Channel channel-1 on cxn-1 was closed unexpectedly
    20:00:54 ERROR [AMQP Connection 192.168.0.200:5000] Connection cxn-1 was closed unexpectedly
    20:00:54 INFO [lyra-recovery-2] Recovering connection cxn-1 to [Lcom.rabbitmq.client.Address;@271429c8
    20:00:54 INFO [lyra-recovery-2] Recovered connection cxn-1 to amqp://192.168.0.200:5000/
    20:00:54 INFO [lyra-recovery-2] Recovering channel-1 on cxn-1

and add one more line:  

    20:00:54 INFO [lyra-recovery-2] Recovered channel-1 on cxn-1