Add to CULU theme via customizer an option to select one hero image to mobile, tablet, and desktop devices.

[manolobevia]

Right now, you can add different hero images to mobile, tablet, and desktop devices (ex: https://vet.library.cornell.edu/), or just one image but with the possibility to crop manually this single image, then upload via customizer. I have noticed the rest of the units use the same image for mobile, tablet, and desktop and uploading the same image 3 times. For example, https://dev-uls-library-cornell-edu.pantheonsite.io/, just has a hero image for desktop. If you want to add the same image to mobile and tablet, you will need to add the hero image again and twice.