Filter target host logging from stdout of main process
Change I60e1eb4b630d4779e2659310475b1973c783c6d8 implemented structured
logging from the target host to the deploy host which resulted in a lot
of noise on stdout of the main process. The handler for stdout has been
configured with a new filter to omit everything from the targets. We
should work on implemented specific panes or log files for such output.
The generic log.Filter class should help when it comes time to
implement such filtering of other handlers (especially if we're to
accept user provided filters) as it implements a very general syntax. Or
it's just crazy and unnecessary. Who knows? I'm very tired.