add main to package.json

package.json

@@ -9,6 +9,7 @@
     "build": "NODE_ENV=production webpack --config webpack.config.prod.js",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
+  "main": "index.js",
   "author": "Cassie Tarakajian",
   "license": "MIT",
   "repository": {