Added setAnimationSpeed() function to replace setFPS() in SpriteImage

The definition of setChangeFPS() in SpriteImage.js is wrong or at least confusing:
        /**
         * Set the elapsed time needed to change the image index.
         * @param fps an integer indicating the time in milliseconds to change.
         * @return this
         */
        setChangeFPS:function (fps) {
            this.changeFPS = fps;
            return this;
        }

Here, the integer indicates the time between frames. That is, high integer, fewer frames-per-second (FPS). Low integer, higher FPS.

That is, the parameter does exactly the opposite of one would expect.

Re-done original unclean pull-request.
See https://github.com/hyperandroid/CAAT/issues/106