Switch to non-jQuery version of Cropper

[GCheung55]

Ember is moving away from jQuery. Consider switching to use non-jQuery version of Cropper;

[RobbieTheWagner]

Definitely a good idea 👍. Do you have any interest in submitting a PR for it?

[0000marcell]

I was solving this issue, but got stuck...
i'm able to use cropperjs and everything works fine but when i call getCroppedCanvas() a second time nothing is returned
the relevant code:

getCroppedAvatar() {
      let cropper = this.get('cropper'),
          croppedImage = cropper.getCroppedCanvas();
      this.set('croppedAvatar', croppedImage);
    }

and the cropper declaration:

let image = document.querySelector(
      properties['cropperContainer']);
    this.set('cropper', new Cropper(image, properties));

the second time getCroppedAvatar() runs nothing is returned from getCroppedCanvas()
any help is appreciated, the entire code can be seen https://github.com/0000marcell/ember-cli-image-cropper

[RobbieTheWagner]

@0000marcell would you mind going ahead and opening a PR, so we can see the diff? I can help try to debug from there.