Add ESLint

[vmarchesin]

Added support for ESLint. Fix #1

• [X] airbnb style
• [X] Support for prettier rules, avoiding conflict
• [X] Support for husky hook

Changes made

• husky no longer formats the code. It will run eslint during the pre-commit hook and fail the commit if eslint doesn't pass. To format the code you can either fix using the --fix option manually or use npm run format.

[vmarchesin]

@drcmda Could you perform a quick check to see nothing is broken? Also let me know if you want to enforce/disable any other rules so I can change it.