Create better exports alias

[ORESoftware]

In the readme, for programmatic usage, I see these two exports:

var beautify = require('js-beautify').js_beautify,
var beautify = require('js-beautify').js,

...why not do this for the programmatic API?

var beautify = require('js-beautify').beautify,

so that users can do this:

const {beautify} = require('js-beautify');

or

import {beautify} from 'js-beautify';

[bitwiseman]

@ORESoftware If we were to make require('js-beautify').beautify it would need to return the same thing as require('js-beautify'). And we'd need to add tests for that import style.

Other than that, seems reasonable. PR welcome.