title: rabbitmq keepalive timeout error
body: <p>Below is part of my rabbitmq log file.</p>
  
  <p>=ERROR REPORT==== 22-Dec-2016::09:36:20 ===
  closing MQTT connection "xxx.xxx.xxx.xxx:11030 -> xx.xx.xx.xx:1884" (keepalive timeout)</p>
  
  <p>=ERROR REPORT==== 22-Dec-2016::09:36:20 ===
  closing MQTT connection "xxx.xxx.xxx.xxx:14653 -> xx.xx.xx.xx:1884" (keepalive timeout)</p>
  
  <p>=ERROR REPORT==== 22-Dec-2016::09:36:22 ===
  closing MQTT connection "xxx.xxx.xxx.xxx:14494 -> xx.xx.xx.xx:1884" (keepalive timeout)</p>
  
  <p>I think this is closing MQTT connection by keepalive timeout.
  Is this normal?
  These are repeatedly shown. so log disk is full.
  Is there way of connection is keep alive?</p>