Update gallery.css

Added proper pointer-events to the initialization, this way the user can interact with the first slide the first time the slider is executed.
Update _gallery.scss

Added proper pointer-events to the initialization, this way the user can interact with the first slide the first time the slider is executed.
Merge pull request #14 from JoePerkins/master

Disable pointer events on gallery items, enable on the first-of-type as inititalizer