Disambig items have thumbnail, title, and Wikidata description

Collecting the disambig titles and the link html in JS code
to avoid having to parse the HTML in Java.

Using page titles to request page images (thumbnails) of
the disambig items.

Using page titles to request wikidata IDs from Wikipedia,
then using the Wikidata IDS to request Wikidata descriptions.

TODO for later:
The page images cache should probably be centralized and refactored.

Change-Id: Ic06de893a4ff6aa3faad57d7999ebf5f74b82d0a