Add lint script to package.json

package.json

@@ -3,6 +3,9 @@
   "version": "0.1.0",
   "description": "NodeJS MTProto API Telegram client library,",
   "main": "index.js",
+  "scripts": {
+    "lint": "eslint ."
+  },
   "repository": {
     "type": "git",
     "url": "git+https://github.com/gram-js/gramjs.git"