Send log msgs to file '{cluster}.log' as well as console.

Default log level is INFO to console, DEBUG to logfile
--verbose changes console log level to DEBUG as well
logfile gets timestamp modulename level msg, console gets just msg

Fixes: #4468
Signed-off-by: Dan Mick <dan.mick@inktank.com>
do not default to verbose

Signed-off-by: Dan Mick <dan.mick@inktank.com>