CCBC-227 Use specific error code for missing node in vbucket map

Change-Id: Ia2efb773b87109ed08e190958e628f1382e21238
Reviewed-on: http://review.couchbase.org/28052
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>