add playSlideshow and stopSlideShow actions

[8BigFish88]

Passing an array of images to a new "hoverEffect" object will allow to build a slideshow with the. The action "playSlideshow" will activate the slideshow. The "stopSlideShow" will allow to stop it.

With this branch change is not necessary to pass always the image1 and image2 if and array of images is passed.

The old hover effect functionalities will still work.