Add "unmount" component animation

[annmirosh]

Hi,

Thanks for the awesome lib!

I'm wondering if it is possible to set up animation before the moment when component is unmounted (to achieve something like "animated disappearing").

Is it possible in your lib somehow or it is only possible with manual adding "out" classes like "spaceOutLeft"? Other words I have a popup and I want it appear with "spaceInLeft" effect and disappear with "spaceOutLeft", could you please suggest how can I do it with react-magic?

Thanks!