Add neutral button

[Nicola De Fiorenze]

Hi, I would like to contribute to your project by adding a neutral button.

It would be useful, for example, to show a "later" button.
Can I submit a pull to request?

[Piotr Głębocki]

Hi @defio
Looks like good idea. We will verify it and I will check your pull request.
Thanks for contribution

[Piotr Głębocki]

"Neutral button" feature were merged. Will be added to release 2.1.0