get images in views only if co-ordinates are set else return empty so that original image can be output using rewrite

If image styles are only have EPSA effects and if user doesn't select the crop area ( if original image is pre-croped ex: image having face croped) then there will no need to generate the image for that particular images style.
This is also useful when need to show different product parts using views and when image style return empty then we can rewrite to show original image.
Currently images are generating for all styles whether crop are not selected.