Bug: custom overlay won't close when pressing `esc` button or clicking outside (once having focus)

[yairEO]

Go here:
http://react-day-picker.js.org/examples/input-custom-overlay

1. (Mouse) click on the datepicker input, an "overlay" should show.
2. Click on any white area within the overlay, then press the esc key
3. Overlay should close, but nothing happens
4. Click anywhere outside of the overlay, and again the overlay should close but it's not.

This also happens when giving focus to the custom input within the overlay in the demo page.

[joafeldmann]

Further the overlay opens again / stays open when you focus the input, hit esc and then press/hold the esc key again