Update buttons_sleep() for auto-off restart case

Update buttons_sleep() for auto-off restart case

buttons_sleep() now first sleeps until the rocker switch is turned off
before then sleeping until it is turned on.  This allows the function to
be used for the auto-off case, where the lamp must stay in auto-off when
the rocker switch is still in position B.  To wake from auto-off manually,
one simply turns the rocker off then back to either position A or B.