Reflect parent of Archiver class

Archiver objects inherit the Node `stream.Transform` methods. See https://www.npmjs.com/package/archiver, "API" subheading (Or `lib/core.js`, line 56 and https://www.npmjs.com/package/readable-stream).

archiver/archiver.d.ts

@@ -16,12 +16,13 @@
 /// <reference path="../node/node.d.ts" />
 declare module "archiver" {
     import * as FS from 'fs';
+    import * as STREAM from 'stream';
     
     interface nameInterface {
         name?: string;
     }
         
-    interface Archiver {
+    interface Archiver extends STREAM.Transform {
         pipe(writeStream: FS.WriteStream): void;
         append(readStream: FS.ReadStream, name: nameInterface): void;
         finalize(): void;
@@ -38,4 +39,4 @@ declare module "archiver" {
     }
     
     export = archiver;
-}
+}