Add files prop to package.json

Author: kdenz

package.json

@@ -5,6 +5,10 @@
   "main": "lib/commonjs/index.js",
   "react-native": "js/index.js",
   "module": "lib/module/index.js",
+  "files": [
+    "/js",
+    "/lib"
+  ],
   "scripts": {
     "run:ios": "node node_modules/react-native/local-cli/cli.js run-ios --project-path \"./example/ios\"",
     "start": "node node_modules/react-native/local-cli/cli.js start --projectRoot example --watchFolders $PWD",