Add the options 'first-day' and 'no-extra-rows'.

The first-day attribute sets the first day of the week.
The no-extra-rows attribute disables adding empty rows to the calendar.

since this option acts as a value, the `true` part is not necessary. 

```html
<div pickadate no-extra-rows></div>
```

Then you could check `noExtraRows = attrs.hasOwnProperty('noExtraRows')`