Multi-select pages to download

This is a user request: On an issue page, have the ability to select multiple pages to download as bulk jpgs or pdfs. 

https://oregonnews.uoregon.edu/lccn/sn83025151/2015-02-11/ed-1/

User suggested a check box to select pages and then download as jpgs or pdfs, probably in a zip folder. 

Needs testing... 