Added vertical scrolling on touch devices

When the plugin is used on a touch device and takes up all of the available screen space, it wasn't possible to scroll any further vertically. To make it usable in this case, I added an option to not prevent scrolling when there are mostly vertical scroll gestures.

The option is disabled by default to not break backwards compatibility. If you want to activate it, start the plugin like this:

    $('yourSelector').ThreeSixty({
      // other options...
      verticalTouchScroll: true;
    });

If not activated, the patch shouldn't have any effects.

I also corrected some typos in comments, I hope that it is ok to have both in one pull request, because I forgot to make a commit for this on it's own.

Keep up the good work,
Marc