It would be great to have `onChangeHue` event

[t1m0n]

Hey @omgovich! Thanks for a great colorpicker.

It would be great if we could get current hue value. It could be helpful when, for example, we need to style popup arrow with current hue color. react-colorful doesn't trigger onChange event when saturation placed on #000000, user can change hue and visually it changes but event is not triggered and there is no proper way to get the hue value.

Current workaround is just to get values from DOM element