Timeline.js: Explore media types

[csbailey5t]

Timeline.js can incorporate a number of media types into slides: https://timeline.knightlab.com/docs/media-types.html.

Given the current fields and ways of attaching media in an Omeka record, we can't take advantage of this rich media support. Could be good to explore ways to attach youtube videos, sound files, and such to records to incorporate into the timeline.