CBQE-1380: add vbuckettool tests

Change-Id: I8788242c74a0a7f7b6b740b0eb3b17d0254c23e4
Reviewed-on: http://review.couchbase.org/38178
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>