0485 contentstate canvas region

[giacomomarchioro]

Fix #591.

Url encoded using: https://iiif.io/api/content-state/1.0/#631-javascript (different from what proposed in the issue).

Further testing might be necessary after deployment.

[glenrobson]

Merge to local branch then check tests and if OK group happy to merge.

[giacomomarchioro]

I wasn't able to check it locally due to some conflicts with jekyll. I'll try again in another computer.

[glenrobson]

I think to move this locally we need to:

If you haven't already cloned the IIIF repo:

git clone https://github.com/IIIF/cookbook-recipes.git
cd cookbook-recipes

2. Add the fork as a remote

git remote add giacomo https://github.com/giacomomarchioro/cookbook-recipes.git
git remote -v

3. Fetch the forks branches:

git fetch giacomo

4. Check out the branch locally

git checkout -b 0485-contentstate-canvas-region giacomo/0485-contentstate-canvas-region

5. Push to the IIIF repo

git push origin 0485-contentstate-canvas-region

6. Create new pull request with the IIIF repo version of 0485-contentstate-canvas-region