Allow Editing Giveaways' End Dates [Update 2.0]

Sometimes I create a giveaway and then I see that I messed up the end date, or I just want to let it run a bit sooner or longer for some reason (i.e. the giveaway didn't get enough entries to give me CV yet), but then there are already entrants, so I can't just delete the giveaway and create a new one (technically I can, but it would be too much of a hassle). So it would be nice if we could edit the end date of a giveaway, within the minimum and maximum limits of 1 hour and 30 days, of course. I believe this would be really helpful.

Update: The minimum and maximum limits would be from the start date, obviously, and you would be allowed to edit only once automatically (having to go through support if you needed to edit it more times), to prevent people from editing it forever and possibly always keeping the giveaway on the front page. And you would lose a slot every time you edited the end date of a giveaway, to keep things fair (some situations could be slot-losing free).