QPID-5434: send timestamps with correct typecode

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1552400 13f79535-47bb-0310-9956-ffa450edef68
QPID-5435: use the setContentObject() method to set string content (i.e. assume it is utf8)

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1552401 13f79535-47bb-0310-9956-ffa450edef68