PYCBC-108: Pass ascii=false to json.dumps

Change-Id: If1b1cb8d9824461628865101ab8ffeac4a7b8ded
Reviewed-on: http://review.couchbase.org/26330
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Reviewed-by: Rami Chowdhury <rami@esplorio.com>
Tested-by: Mordechai Nunberg <mnunberg@haskalah.org>