Add couchstore to newvtree manifest

Change-Id: I33e3892139302b7dced6a03e2569449439014ff6
Reviewed-on: http://review.couchbase.org/27068
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Volker Mische <volker.mische@gmail.com>