Bookmark plugin: fix for delicious import with queues enabled

Bookmark plugin: fix for delicious import with queues enabled

We were passing DOM nodes directly into the queues for the final bookmark import stage; unfortunately these don't actually survive serialization.
Moved the extraction of properties from the HTML up to the first-stage handler, so now we don't have to worry about moving DOM nodes from one handler to the next. Instead passing an associative array of properties, which is fed into the Bookmark::saveNew by the per-bookmark handler.