WHISTLE-1441: webseq logger, for building web sequence diagrams (hopefully)
WHISTLE-1441: track the ACDc Queue process' AMQP queue name in the agent listener process
WHISTLE-1441: send the next agent (and update the queue as appropriate), from the gen_server rather than sending the current agent queue to the calling process
WHISTLE-1441: handle when there's no strategy state