optimize webpack bundling, minimize gateway JS

src/Browser.ts

@@ -1,5 +0,0 @@
-(window as any).global = window;
-(window as any).Buffer = (window as any).buffer.Buffer;
-const rippleApi = require('xrpio')
-window['xrpIO'] = rippleApi.xrpIO
-

src/Gateway.ts

@@ -1,8 +1,7 @@
-(window as any).global = window;
-(window as any).Buffer = (window as any).Buffer || require('buffer/').Buffer;
 (window as any).buffer = (window as any).Buffer
-import { xrpIO } from 'xrpio';
-(window as any).xrpIO = xrpIO;
+//import { xrpIO } from 'xrpio';
+
+declare const xrpIO
 declare const DATA_HASH: string
 
 const api = new xrpIO("wss://s.altnet.rippletest.net:51233")