MB-8903: Update according to transport spec changes

The Mutation and Deletion command now include an nmeta
field. Currentlty it is expected to be 0, hence no
additional meta information is attached.

Change-Id: I5d2901ad6ad451802fd4e8a8facec95154a73790
Reviewed-on: http://review.couchbase.org/32324
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>