QPID-4562: Changed Message.reply_to to accept a address string.

Previously it would accept only an instance of Qpid::Messaging::Address,
but now will create an instance from a string if necessary.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1442149 13f79535-47bb-0310-9956-ffa450edef68
NO-JIRA: Changed references to "URI" to be "address string".

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1442150 13f79535-47bb-0310-9956-ffa450edef68