QPID-5161: use a full test implementation of MessageMetaDataType to ensure that the metadata can be decoded from the store if the test finds itself on the wrong side of a race with the garbage collector

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1525745 13f79535-47bb-0310-9956-ffa450edef68
QPID-5161: make QBTC use the canonical working dir, and throw an exception if the relative path handling cant generate an appropriate path

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1525746 13f79535-47bb-0310-9956-ffa450edef68