No mate, unfortunately no iPhone other than the 5S and above will get that added later on. However what you are going to get with iOS8 is a time lapse video function which too is pretty neat.
As for your app question, a quick App Store search turned up this one https://appsto.re/au/5d8oE.i
which looks quality and seems fair as it relies on in app purchases. Maybe give it a try, the reviews sound positive.