Added 0.40 compatibility and updated usage in README

[syousif94]

I updated the headers for react-native 0.40 and updated the JS in the usage instructions.

[meznaric]

Thanks for PR. I somehow missed it. I will merge it in next couple of days.

[meznaric]

Why would we want that? I think it makes more sense to keep original size.

[syousif94]

Hi sorry, I did not realize further commits would modify this pull request. I think it would be helpful to let users set a max resolution though because loading a cropped full resolution photo from the camera album has a noticeable delay on my 6S. I can add that feature or just close this pull request.

[meznaric]

I think it's a good feature to have especially if delay is noticeable. Did you think about JS API already?

So far we have:

.cropImageWithUrlAndAspect(imageUrl, aspectRatio)
.cropImageWithUrl(originalImage.uri)

without breaking backwards compatibility we could introduce something like
.cropImage(originalImage.uri, options)
where options would be:

{
    maxWidth: 150, // optional, default no max width
    aspectRatio: ReactNativeImageCropping.AspectRatioSquare, // optional, default not locked
}

It would be easy to extend as well.

[syousif94]

Yeah sounds good, I'll update the pull request over the weekend.