Update ProQuest.js

See https://forums.zotero.org/discussion/40821/zotero-not-recognizing-books-chapters-dissertations-in-proquest-psycinfo/

(Maybe we should wait for more examples of different types.)
the example Keith just posted in that thread has 
Handbook/manual, Edited Book, Book

I wonder if it wouldn't be worthwhile to sacrifice some efficiency and do this with an if/ else if loop where we can actually test for a regex match rather than trying to guess every single possible full string. @aurimasv - thoughts?