fix(ngAnimate): make sure that the class value passed into addClass/removeClass is the base class string value

When the animation `addClass` or `removeClass` callback functions were called, they were passing in `CLASS-add` and `CLASS-remove` into the functions. This is incorrect, it should just be `CLASS`.

To make the fix, some of the code inside of `animate.js` had to be changed around to avoid redundant code. `animation()` was changed `$animateProvider.register` within the animate.js file.