Switch back from node-fetch to isomorphic-fetch

node-fetch utilizes Node.js standard library to work, so it
cannot be used in browsers. So we need to switch back to
isomorphic-fetch which works both in browsers and Node.js.

Change-Id: Idc8d18021a3226fb8339c99e3009dc53cbc15b2a

package.json

@@ -25,8 +25,8 @@
   "homepage": "http://www.openstack.org/",
   "dependencies": {
     "babel-polyfill": "^6.9.1",
-    "loglevel": "^1.4.1",
-    "node-fetch": "^1.5.3"
+    "isomorphic-fetch": "^2.2.1",
+    "loglevel": "^1.4.1"
   },
   "devDependencies": {
     "babel-cli": "^6.10.1",

src/index.js

@@ -1,5 +1,5 @@
 import 'babel-polyfill';
-import fetch from 'node-fetch';
+import fetch from 'isomorphic-fetch';
 import log from 'loglevel';
 
 log.setLevel('INFO');