Use JSHint in addition to JSLint during development

I had [`laxbreak`](http://www.jshint.com/docs/options/#laxbreak) enabled in the .core repositories due to warnings about ternary expressions formatted like this:

```js
var foo = someConditional
  ? yes
  : no;
```

Without that option, jshint complains. Or we decide to format such expressions differently. E.g.

```js
var foo = someConditional ?
  yes :
  no;
```

I believe the above does not trigger the error.