setClass should be broken up into addClass + removeClass JS animations

[matsko]

setClass is run when ngClass changes and both addClass and removeClass are run at the same time. This works fine, but it also requires a setClass animation to be defined within the JS animations.

This because annoying when you have to watch for CSS class changes within addClass, removeClass and setClass. Instead setClass should break down to addClass and removeClass if setClass is not defined on the animation.