Add ability to create JPG images from PDF page

[homestar9]

No description provided.

[mjclemente]

Thanks for submitting this! And I'm sorry it's taken me so long to get around to reviewing it.

The method itself is great, and exposing the renderImage functionality seems useful.

My only concern is that, as it is, it's doing a little much, and I'd like to keep the project focused on the PDFBox functionality.

My first impression is that the functionality related to resizing and cfimage could be removed. If/how the resulting image is resized seems like more of an application level decision.

Happy to hear your thoughts if you think otherwise - and if you don't want to make the changes, I can merge this and then make them myself - not trying to make more work for you.

Again thanks!