Make follow/unfollow buttons work asynchronously

The point of the animation is to show that activity is happening while the network is busy. It doesn't make sense to only play the animation once the action is complete. The point of the animation is to be responsive to the user and illustrate that we've receives her command and are acting upon it. So, the animation must play immediately after the button is clicked - and the ajax request should also begin immediately after the button is clicked.