CBIDXT-83 Add support for Drop Index/Update Stream

KVSender is now able to make Drop Index/Update Stream Requests
Few fixes required in protobuf

Change-Id: I084b1c588221474efc49c4a8166a3906e1bbff4d
Reviewed-on: http://review.couchbase.org/38831
Reviewed-by: John Liang <johliang00@gmail.com>
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Tested-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>