Use classnames & lint fix

[rhobot]

In React 0.13, classSet will be deprecated and using classnames is recommended.

[cain-wang]

Thanks for embracing the new feature!
Probably we could do something automatically when developers give an array or an object to className, we automatically wrap the value using classnames?
Like:

r(SomeComponent, {
  className: ['class1', 'class2'] => className: classnames('class1', 'class2')
})
r(SomeComponent, {
  className: {'class1': true, 'class2': false} => className: classnames({'class1': true, 'class2': false})
})

[rhobot]

I agree, but this may confuse some users because className is always a string in React.
But if most of us agree, I'm happy to add the feature.