Convert from show()/hide() to using classes

jQuery's show/hide/fadeIn/fadeOut methods makes changes to the
style attributes of elements. That makes them rather hard to override
their visibility, without adding an entire API to the module to do so.

This replaces the default animations with one using classes to control
visibility and only animates the animatable properties using
the style attributes.

Follow-up to: Iadaae3fb9ae1899e12605d653b2688616b8f7c40

Change-Id: I4652ade66c6de864ee3e74b3817ed9b93967ce3d