Add option for curve

[Muhammad Dicky Hidayat Latif]

This great, I have same concept with this package on my app but in my app I can set curve on my own. So it will be great if another dev can set his own curve. And this type of animation is great on tab, on my project i have function to trigger reverse animation when switch between tab, this also great if we can reverse the animation from this package.

[Aurélien Lepage]

Duplicate of #22
Curve param on animations will be released in 0.1.3.