HORNETQ-1224 Fix race on QueueImpl.deliver() when paging.
https://bugzilla.redhat.com/show_bug.cgi?id=972444

Case was actually tracked down by Andy Turner and Howard Gao.

Conflicts:
	hornetq-server/src/main/java/org/hornetq/core/server/impl/QueueImpl.java
	tests/jms-tests/src/test/java/org/hornetq/jms/tests/HornetQServerTestCase.java