Shared eslint config for Sinon

The [sharable eslint config][docs] for all Sinon.JS projects.

The package includes all the dependencies to have a working eslint
setup that works with the configuration. Adopting projects will only
need to install @sinonjs/eslint-config.

Install

``bash
$ npm install @sinonjs/eslint-config --save-dev
`

Usage

Add this to the package.json:

`json
{
"eslintConfig": {
"extends": "@sinonjs/eslint-config"
}
}
`

Create a .browserslistrc in the root of the project

`
> 0.5%
last 2 versions
Firefox ESR
not dead
not IE 11
not op_mini all
maintained node versions
``

Visit browserslist.dev to see what this translates to.

[docs]: http://eslint.org/docs/developer-guide/shareable-configs