Prefer native fetch

ui/app/services/token.js

@@ -1,5 +1,5 @@
 import Ember from 'ember';
-import fetch from 'fetch';
+import fetch from 'nomad-ui/utils/fetch';
 
 const { Service, computed, assign } = Ember;
 

ui/app/utils/fetch.js

@@ -0,0 +1,6 @@
+import fetch from 'fetch';
+
+// The ember-fetch polyfill does not provide streaming
+const fetchToUse = window.fetch || fetch;
+
+export default fetchToUse;