Add dc.identifier.thumbnail support for WorldCat.
Add optional object linking.
Update README language for thumbnails/urls
Merge pull request #1 from ruebot/7.x-TN-for-WorldCat

Update README language for thumbnails/urls
Add access check and explicitly use object ID.
Merge pull request #2 from adam-vessey/7.x-TN-for-WorldCat

Add access check and explicitly use object ID.
Default value missing, delete all the vars.
Merge branch '7.x-TN-for-WorldCat' of github.com:jordandukart/islandora_oai into 7.x-TN-for-WorldCat
Merge pull request #52 from jordandukart/7.x-TN-for-WorldCat

Add TNs for WorldCat, another way to append links back to the object.