Failed to parse key with square brackets mixed with dots

The expected result of `qs.parse('a=1.2&b[0].c=3')` should be

``` js
 { a: '1.2', 'b[0].c': '3' }
```

In fact we get

``` js
{ a: '1.2', b: { '0].': '3' } }
```

Just for a note, `stringify` works well

```
> qs.stringify({ a: '1.2', 'b[0].c': '3' })
'a=1.2&b%5B0%5D.c=3'
```
