JSCBC-143: Split SpatialQuery to its own class to make docs straightforward.

Change-Id: Ifbe4d21be00a7fae803c932bc10e91cd7b2b59d3
Reviewed-on: http://review.couchbase.org/42559
Tested-by: Brett Lawson <brett19@gmail.com>
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>