As we've added features, the design of the file attachment boxes has gotten a

little bit crusty. We ended up in a situation where we had an icon, a

thumbnail, a caption, a filename, some buttons, and a drop-down menu. This was

way overly complicated, and managed to stuff a bunch of UI into a small area,

making even the thumbnails pretty useless.
This change re-imagines the file attachment boxes with simplicity as the

primary goal. When looking at the page, the only visible information is the

thumbnail and the caption. The thumbnail is a new "HD" thumbnail which is the

full width of the file attachment box. Hovering the mouse over a file box will

trigger an animation that will scroll across the full thumbnail, which makes it

possible to get a lot more information out of it.
Additionally, other commands (such as updating, downloading, adding a comment,

or deleting) are all shown in a menu on the left which is shown while hovering

over the file attachment.
Internally, this changes file attachments to always render via the javascript

views. We previously had a wacky scenario where the initial page load would

render the HTML in a django template, and then the javascript code would

"import" existing file attachments. Newly-created file attachments would be

rendered from javascript. This resulted in a duplication of the template data

between django templates and the backbone view, except there wasn't an exact

1:1 parity between the two. Rendering entirely from javascript cleans up the

code significantly.
I've posted a video of the animation at

https://www.dropbox.com/s/lyohd4firvby0th/new-file-attachments.mov?dl=0

Added, deleted, and updated file attachments.
Tested that animation started and stopped when I expected it to, and that

  various edge conditions and mouse trickery didn't result in wacky animation.
Checked links for every command.
Ran unit tests.
Ran js-tests.