support className

[waynebrantley]

<SwitchButton className="blah" />

should output that className along with your normal output of classes.

[willianjusten]

Oh, that's true. We have:

<div className={disabled ? 'switch-button disabled' : 'switch-button'}>

We can introduce a separated variable to concanate all classes.

I'm not working on this project anymore but if you want to send a PR.