JSCBC-16: Add unit test for bulk load

Change-Id: I04ffe125204b6d554e4236f22bec3aea093a0a16
Reviewed-on: http://review.couchbase.org/25739
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>