Add fields for carrying poison ack cause and some utility constructors.

git-svn-id: https://svn.apache.org/repos/asf/activemq/activemq-cpp/trunk@1463777 13f79535-47bb-0310-9956-ffa450edef68
Ensure properties get set correctly and use locally configured settings when uri doesn't override them

git-svn-id: https://svn.apache.org/repos/asf/activemq/activemq-cpp/trunk@1463778 13f79535-47bb-0310-9956-ffa450edef68