Merge pull request #85 from tomaash/patch-1

In browsers check for XMLHttpRequest, not window

lib/core/dispatchRequest.js

@@ -11,7 +11,7 @@ module.exports = function dispatchRequest(config) {
   return new Promise(function (resolve, reject) {
     try {
       // For browsers use XHR adapter
-      if (typeof window !== 'undefined') {
+      if ((typeof XMLHttpRequest !== 'undefined') || (typeof ActiveXObject !== 'undefined')) {
         require('../adapters/xhr')(resolve, reject, config);
       }
       // For node use HTTP adapter