In cases were pub sub is used with large numbers of consumers / producers and destinations, the number of routing sessions can grow really fast.  lets shutdown sessions once they are idle for over 2 seconds.

git-svn-id: https://svn.apache.org/repos/asf/activemq/activemq-apollo/trunk@1440513 13f79535-47bb-0310-9956-ffa450edef68