Fixing ProQuest search, widening ebrary's domain

ProQuest search results now include ebrary e-books in an extra tab. Zotero scrapes were returning everything regardless of which tab was visible, and these extra items caused the ProQuest translator to crash.

This fix changes the scrape results based on which tab is visible (database results or e-books), excludes some invaild sidebar links from the results, and calls the ebrary translator to handle ebrary e-book results. The ebrary translator was updated to handle links that come from ProQuest.
Yes, the ebrary results that now appear in ProQuest search go to the ebrary domain. (Unfortunately, following those ebrary URLs is the only way to scrape the e-book metadata as ProQuest only lists the titles on its own page.) I'll update the translator with that isBookmarklet function to leave off ebrary results for the bookmarklet users.