USB ports and GPIO power stay on while UP Squared board is off

Is there a way to shutdown power completely from the UP squared board? I'm running as a battery powered device and when the device is off, all the connected (USB/GPIO) items stay on.
If this isn't possible, would anyone know an easy way to rig up some kind of timed I2C power relay which would cut power say 5 seconds after an I2C signal (allowing time for the up board to power down)

Cheers
Russell