allow to pass data parameter in trigger as string

I ran into this issue when I tried to pass string as a data parameter in one of the components. For example:
```js
this.trigger('eventName', 'string');
```

Based on the implementations and specs I assumed that the first argument in `trigger` always represents event name and the the last argument (if present) is a data parameter. 

PS sorry about the `No newline at end of file`. I have to research how to turn it off.