QPID-4742: add option to create a copy of the initial config file, either at a specified location or as initial-config.json in the current directory

merged from trunk r1467932


git-svn-id: https://svn.apache.org/repos/asf/qpid/branches/0.22@1469900 13f79535-47bb-0310-9956-ffa450edef68