Error codes on reporter.js for easier bypass

Hi

Sometimes it's useful to add a JSHint bypass on the code, with JSHint comments; if you want to write a bookmarket, for instance, JSHint will complain with this:

`Label 'javascript' looks like a javascript url.`

The the following line can be added to bypass it:

`/* jshint -W029 */`

However, to do that one must be able to read the **error code**. So, with this patch, the line above will look like:

`Label 'javascript' looks like a javascript url. (W029)`

Stating that it's a warning `W` and the error code `029`.

Hope you find it useful.

Thanks