https://issues.jboss.org/browse/HORNETQ-1137 Optimization on queue-delivery, After this change we are not holding a lock on the queue while the consumer is delivering the packet to the client
also  Fixing groupIterator.remove as that would cause concurrentModificationException on the groupMaps
Merge pull request #889 from clebertsuconic/master

Optimization on queue.delivery . Delivery packet being done outside of lock.