display topic/channel in logs to disambiguate multiple Reader instances
Merge pull request #27 from mreiferson/topic_channel_logs_27

show topic/channel for connection logs
conn: make public
reader/writer: consolidate into conn
reader: add heartbeat_interval to Configure()
reader/writer: add output buffering options
reader/writer/conn: move timeout and connect responsibility
reader/writer: move read loop into Conn
reader/writer works