Internal animation changes

Internal animation changes

 - Changed animation system to avoid creating/destroying SceneGraph::Animators each time the target object is connected/disconnected from the stage
 - Removed use of boost::function for animator functions

[Problem]  AnimatorConnector will create a new SceneGraph::Animator each time the target object gets connected to the stage.
           SceneGraph::Animators will be deleted by the SceneGraph::Animation whenever the target object is disconnected.
[Cause]    n/a
[Solution] AnimatorConnector creates a SceneGraph::Animator once and notifies to it whenever the target object is connected/disconnected.
           SceneGraph::Animation will only remove Animators when the target object has been destroyed.

Change-Id: I0f35e85b8bf150cd954197fe6d213aad2d9f9c89