Mostly additional metrics

• ibmmq - Add more attributes that can be MQINQ'd
• mqmetric - New metric qmgr_active_listeners (ibm-messaging/mq-metric-samples#183)
• mqmetric - Add qmgr description as tag (ibm-messaging/mq-metric-samples#184)
• mqmetric - Add metrics.txt to list the available metrics that do not come from the amqsrua-style publication