New: Custom eslint-skip HTML comment skips blocks (fixes #69)

[btmills]

<!-- eslint-skip -->

```js
{
    // This code block is hidden from ESLint.
    "hello": "world"
}
```

```js
console.log("This code block is linted normally.");
```

[btmills]

This has been released in v1.0.0-beta.7.