Added the ability to specify opening and closing animation props

[davidrichard23]

My specific use case is that the image in my Lightbox uses resizeMode='cover' while not active and resizeMode='contain' while active -- so basically it's cropped while in a list and not cropped while open.

During the closing animation, it would keep the contain prop until the animation was finished. This resulted in black bars around the image until the end of the animation and then it would instantly pop to the cover prop which looked terrible.

I found that by setting the cover prop before the close animation starts, everything works great.

I'm unsure if this was the best way to accomplish this so I'm open to any feedback anyone has.

[brycepavey]

I had the same issue, would be great if this could be merged in!

[RWOverdijk]

I tried this, and the problem just turns around when the image doesn't have an edge to edge size. It'll just jump and then resize, which I think looks worse.