Missing maxHeight and maxWidth options

[zeromancer1972]

There was an issue with that before (https://github.com/fengyuanchen/cropper/issues/816) but the opener closed it by himself, so I create a new one: It would be helpful if the cropping area could support max height and width (as it does with min height and width). Thanks - its a neat plugin!

[fengyuanchen]

.img-container {
  width: 480px; /* use this as the maxWidth */
  height: 480px; /* use this as the maxHeight */
}