Update app.js

@@ -97,15 +97,15 @@ async function handleEvent(event) {
           language: 'en'
         },
         headers: {
-          'Content-Type': 'application/json',
+          'Content-Type': 'application/octet-stream',
           'Ocp-Apim-Subscription-Key': '979dc5d63344438fa4701c62feebb7dc'
         },
-        body: atob(chunk)
+        body: chunk
       };
       
       request.post(options, function (error, response, body) {
           console.log(options);
-        var data=JSON.stringify(body);  
+        var data=atob(body);  
         var text='';
         console.log(data);
         while(data.indexOf('text\\')!=-1)