Require libvbucket

We are currently building moxi with libvbucket in our
product, and this commit is part of the process to simplify
our build process. By removing everything we don't use it'll
be easier to know which parts needs moving over to CMake.

Change-Id: I7258260405f95a281f4fd37b3c98fa4488b0daac
Reviewed-on: http://review.couchbase.org/26951
Reviewed-by: Steve Yen <steve.yen@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>