Make open/close state configurable

[janrembold]

I think it would be good to have an option to control the moment when the panel state toggles from open to close and vice versa.

Proposal would be

• options.animation.setPanelOpenState = 'before' || 'after'
• options.animation.setPanelCloseState = 'before' || 'after'

[VI-Lukas]

Added new class to control animations in last release. Setting open state class before slidedown created a bug where content appeared before slideDown animation could kick in.

Option should be set for new animation contol class.