Added redirect and redirectParamName options.

This allows to set the redirect url for cross-domain iframe transport
uploads, which will be sent to the upload server as form data parameter.

js/jquery.fileupload.js

@@ -1,5 +1,5 @@
 /*
- * jQuery File Upload Plugin 5.6.1
+ * jQuery File Upload Plugin 5.7
  * https://github.com/blueimp/jQuery-File-Upload
  *
  * Copyright 2010, Sebastian Tschan
@@ -75,6 +75,12 @@
             limitConcurrentUploads: undefined,
             // Set the following option to true to force iframe transport uploads:
             forceIframeTransport: false,
+            // Set the following option to the location of a redirect url on the
+            // origin server, for cross-domain iframe transport uploads:
+            redirect: undefined,
+            // The parameter name for the redirect url, sent as part of the form
+            // data and set to 'redirect' if this option is empty:
+            redirectParamName: undefined,
             // Set the following option to the location of a postMessage window,
             // to enable postMessage transport uploads:
             postMessage: undefined,
@@ -316,6 +322,14 @@
             options.dataType = 'iframe ' + (options.dataType || '');
             // The iframe transport accepts a serialized array as form data:
             options.formData = this._getFormData(options);
+            // Add redirect url to form data on cross-domain uploads:
+            if (options.redirect && $('<a></a>').prop('href', options.url)
+                    .prop('host') !== location.host) {
+                options.formData.push({
+                    name: options.redirectParamName || 'redirect',
+                    value: options.redirect
+                });
+            }
         },
 
         _initDataSettings: function (options) {