Fire optional jQuery Event

I wanted to use your plugin to fire an event, so I went ahead and forked it and modded it. 

Basically, now there's an optional `event` option, which takes a string. If it's present, the library will trigger that string on the specific jQuery element, calling any handlers you have for that. For example:

``` javascript
$('input').typeWatch({
    event: 'typewatchEvent'
})

$('input.name').on('typewatchEvent', function(evt{
    console.log("Do something here");
});
```

Feel free to ask me if you have any questions or concerns about merging this!