Add Indonesian icon

As the colour seems a bit off from the one at Wikipedia, and it looks like there's some kind of border and glossy effect on the image, I decided to pull down the SVG from Wikipedia and created a PNG from that (to make the icon look consistent with the others), which I then ran through pngcrush (-force -brute -fix -reduce -rem alla -res 72 -rem allb), and committed that to 6.x-2.x and 6.x-1.x. I hope this is alright with you. :) (And sorry about the wait. :x)