* Use verbose log output for plug-ins
All three plug-ins which support logging (dns, multicast and audio)
should use the verbose log format by default to make sure the log lines
are annotated with timestamp. Introduce a new flag default_verbose for
advanced logs.
* Use default_verbose for host logs as well
Use the new default_verbose flag for advanced logs, to make it more
explicit that we want timestamps for host logs as well.
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