Fix main reference path

Fixes #242

Author: kpdecker

package.json

@@ -21,7 +21,7 @@
   "engines": {
     "node": ">=0.3.1"
   },
-  "main": "./lib/index.cjs.js",
+  "main": "./lib/index.js",
   "module": "./lib/index.es6.js",
   "browser": "./dist/diff.js",
   "scripts": {