Vertical and mouse-driven slider support

I've added vertical slider support by simply adding an additional option, 'direction.' While perhaps not the optimal implementation, whenever any animation occurs, the script now checks this option and alters the left/top, width/height, and delta attributes accordingly.

I also added a 'enableMouse' option allowing the sliders to be driven by the mouse as well as touch if desktop compatibility is required.

Finally I added both these options to the demo and ReadMe. Please pull and enjoy!