Allow XAPooledConnectionFactory to be join an xa transaction - two connection factories in same arjuna jboss jta transaction

In the mdb tck, when plain jms is used for the resources there is a test that uses two connection factories in the same cmt. This causes the underlying tm to xa_join a resource with an active association and the activemq transactioncontext reports an error.

some more detail on https://fusesource.com/issues/browse/ENTMQ-224

Tasks:

1. validate arjuna jta is correct (first thought is that the second resource should be asked to join)
2. support join