$.parseJSON should return `any` instead of `Object`

Here is my test:
```js
var i = JSON.parse('1');
var a = JSON.parse('[1]');
var o = JSON.parse('{"foo":"bar"}');
var s = JSON.parse('"string"');
var n = JSON.parse('null');

i instanceof Object; // false
a instanceof Object; // true
o instanceof Object; // true
s instanceof Object; // false
n instanceof Object; // false
```

JSON.parse returns the `any` type so I think this method should do the same.

More of the discussion regarding this pull request can be found on the original commit 8c23d04a5b4a0505df042a82be90f95adff02d87

https://github.com/borisyankov/DefinitelyTyped/commit/8c23d04a5b4a0505df042a82be90f95adff02d87
Added test for parseJSON
Merge pull request #2199 from styfle/patch-4

$.parseJSON should return `any` instead of `Object`