Small change to Managed Blink for windows

Heya,

I've added a Complete() method to the Managed Blink class that does the same thing as Dispose, but minus setting the device rgb to black before disposing of the hid device underneath (this is to make it easier for apps that run periodically to set the blink color).

I figure if I've found it useful, someone else probably will too :)

Cheers,
Mat