Use innerRef prop instead of ref to avoid warning

[meriadec]

relatable: #2181

[coveralls]

Coverage remained the same at 94.973% when pulling 9262af9 on meriadec:master into c9d0273 on JedWatson:master.

[sungwoncho]

This change will break apps that are relying on ref prop. How do you feel about deprecating ref while adding innerRef rather than removing ref altogether?

[JedWatson]

Thanks for the PR @meriadec

I agree with @sungwoncho - we can't make this change without a major bump, and I'm inclined to implement the new ref forwarding from React 16.3 as the solution to this. In the meantime, we could add a selectRef prop to get rid of the warning if somebody wants to PR that.

[Dem0n3D]

@JedWatson, please, do something with this warning already.