use parallel installed versions in RHEL6

of webob sqlalchemy python-routes and paste-deploy

Change-Id: I290f56eae61c87893639a9e5d29f7fff760452cf
avoid code path causing qpid exchange leaks

Always assume amqp_rpc_single_reply_queue is True,
so that the problematic code path is ignored.
The issue is discussed at https://pad.lv/1178375