QPID-5205: Change ExchangeAdapter to return a model exchange object for alternate exchange

This avoids the possibility of a StackOverflowException when viewing an exchange were a alternate has been
set at declare time (0-10 only).

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1529492 13f79535-47bb-0310-9956-ffa450edef68