Setup npm run prepare

Author: mauriciopoppe

package.json

@@ -22,6 +22,7 @@
   "main": "lib/index.js",
   "module": "lib-esm/index.js",
   "scripts": {
+    "prepare": "npm run build",
     "build": "npm run clean && npm run build:library",
     "build:library": "tsc && tsc -m es6 --outDir lib-esm && webpack",
     "clean": "rm -rf dist lib lib-esm",