Update cropper when options.aspectRatio changed.

[blutarche]

Added below script inside ngCropper directive in dist/ngCropper.all.js

scope.$watch('options.aspectRatio', function() {
  element.cropper('destroy').cropper(scope.options);
}, true);

[srinivasaltair]

@koorgoo Above code is very helpful and it works as expected please accept the pull request so that we can directly use it from boweror npm install without changing the repo code.

I had a question #36 regarding the issue, but this script helped me fix it.

Thanks in advance & @blutarche Thanks