U/salnikov/dm 621

It means that by default (if you do not provide --verbose-all option) logging level is changed (set to INFO/DEBUG) only for logger that is used by data-loader script. If you specify --verbose-all then logging level is changed for all other loggers as well (kazoo, CSS, etc.) I added this option because when I enable INFO logging globally there are too many verbose messages from CSS and kazoo which I do not normally want to see.