PYCBC-260: Default lock timeout is 30, not 15 seconds

Change-Id: Ie58ce4e0aaf60dad6c5ac80c796aee2f256e6075
Reviewed-on: http://review.couchbase.org/42352
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Volker Mische <volker.mische@gmail.com>