RAX120 USB HDD SLEEP

This should be an easy change to add the ability to set a sleep timeout for USB attached hard drives. My RX500 nighthawk would alow my attached drive to spin down when not in use (which is most of the time). I upgraded to the RAX120 due to its 5g port and higher data transfer rate on the USB drive but it is very wastful to have the drives spun up 24/7. I am extremely disappointed with this inefficient oversight.