fix for: https://issues.apache.org/jira/browse/AMQCPP-455

Makes the connection factory config data thread safe.

git-svn-id: https://svn.apache.org/repos/asf/activemq/activemq-cpp/branches/activemq-cpp-3.5.x@1444163 13f79535-47bb-0310-9956-ffa450edef68