Add callbacks and more checks to CCBC-150 test

Change-Id: I125674c6a004efafb63c9934615c6380043ba00d
Reviewed-on: http://review.couchbase.org/28118
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>