Add Lint-staged and lint action on package.json

[josx]

Now we already have eslint with airbnb style on code.

To improve I think would be great to include lint-staged, a lint action in script, and add on test action first the linting process.

Sample:

"scripts": {
"lint": "eslint ..."
},
"devDependencies": {
"lint-staged": "^7.2.2",
},
"gitHooks": {
    "pre-commit": "lint-staged"
  },
  "lint-staged": {
    "*.js": [
      "npm run lint",
      "git add"
    ]
  }