IIIF Presentation API

[pletcher]

We should implement the Presentation API to make it easier to browser commentary images in the IIIF viewer.

[pletcher]

I'm not sure that we need to implement the presentation API, since we're de-prioritizing the image interactions anyway (or just enabling them for users to check the source).

The OSD TileSets that we're using instead are working great so far. Should we just close this/icebox it?