IIIF Manifest URLs

[dleadbetter]

Update the IIIF manifest creation to use the IIIF Cloud URLS (/resources/:uuid/iiif) instead of hard-coding the IIIF server URL. This will allow us to switch servers, or upload different content without making the manifest URLs stale. Here's what happens:

1. User uploads a set of images to Core Data
2. Core Data creates the media_contents records and uploads the files to IIIF Cloud
3. In the background, IIIF Cloud converts the images to PTIF; If the files are large, this may take some time
4. After the upload completes, Core Data generates a manifest using IIIF Cloud

The issue is that if the background job to convert the image to a PTIF has not yet completed, the URL for the source image is stored inside the manifest. This can sometimes lead to issues with Cantaloupe processing and serving the image.

Testing Note

Again for this issue, there shouldn't be any changes that are immediately obvious to the end user. We should test using Core Data that any manifest generated can be viewed as expected using:

• Mirador
• Universal Viewer
• Clover IIIF