If its a of web app I doubt its "complete" as they never really are (I work for a company with a 10 year old web app thats still having changes made to it), so you can go to him and say, "I've put in 3 months so far, you've put in basically none, now it's your turn" and he can handle the next stage of development, bug fixes, feature additions, etc while you take the back-seat for the next few months and handle the fluff work. If he doesn't like this, then maybe consider pulling a zuckerburg