DISPATCH-74: Allow changes to logging configuration of a running router.

Allow UPDATE management requests to log entities to change log settings on a running router.
Use log:MODULE as management ID for log entity representing MODULE.
The generic qdmanage client can be used to modify log settings.

This commit does not include a more convenient client for this task.

git-svn-id: https://svn.apache.org/repos/asf/qpid/dispatch/trunk@1640379 13f79535-47bb-0310-9956-ffa450edef68