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.)
well, the performance difference comes from the indexOf which slows this down dramatically, a factor of 300 if I did that right. http://jsperf.com/if-switch-lookup-table/45