Rewrite slideshow to not have a jquery dependency

[jcoyne]

No description provided.

[marlo-longley]

@jcoyne not sure if you can reproduce this but I am getting an error.

1. Go to a slideshow view http://localhost:3000/?f%5Bpub_date_ssim%5D%5B%5D=2008&view=slideshow

2. Click the first item to open modal ("California", all the way to the left)
3. Result: broken view in modal (vert scrolling all the items)

4. Now click the next arrow, or X out of the modal and open it again

5. Result: correct single-item view in modal, including when you page back to the first item

[jcoyne]

@marlo-longley that seems like stale code because we don't use .querySelector() in this version.