Revert "Revert #174 to allow a working React 16 version with checkmar…

…k icons and centred images into Automattic/wp-calypso. (#199)" (#200)

This reverts commit 2f37504.

package.json

@@ -1,8 +1,8 @@
 {
   "name": "notifications-panel",
-  "version": "2.1.2",
+  "version": "1.3.1",
   "description": "The core notifications panel for WordPress.com notifications",
-  "main": "src/Notifications.jsx",
+  "esnext": "src/Notifications.jsx",
   "scripts": {
     "build": "webpack",
     "build:prod": "NODE_ENV=production webpack -p",