concerning 'query.json' multi-value queries

This adds the ability to specify multiple values without having to pass a json dictionary by splitting value strings with '+OR+' into lists.

For example, if one wanted to search for editions using multiple subjects, currently a json dictionary is required:

    openlibrary.org/query.json?query={"type": "/type/edition", "subjects": ["war", "peace"]}

which will return editions with 'war' or 'peace' as subjects.

It would be nice to be able to do something like:

    openlibrary.org/query.json?type=/type/edition&subjects=war+OR+peace
 (+ obviously having to become %2B)

(sorry for all the whitespace changes...emacs seems to have done this automatically)