[AS7-6348] Upgrade to HornetQ 2.3.0.Final

* update to hornetq latest snapshot
[AS7-6124] JGroups channel in pooled-connection-factory

* add a JGroupsChannelLocator that HornetQ RA can called
  back to get a JGroupsChannel for the JGroups stack defined
  by the pooled-connection-factory discovery-group