updates the '--verbose' behaviour
fixes argument handling of '--max_sleep='
makes changing of the configurations via argument more vocal
now disables other output-modes, when choosing one
adds forgotten 'not' in the write_config_file function
adds error-handling, when no price can be found, when displaying min, avg and max
implements 'UPDATES_ONLY' mode
fixes bug, where MIN_SLEEP_TIME and MAX_SLEEP_TIME caused write_config_file to fail