_bindEvents (element) {
    var events = ['click', 'touch'];

    // Setup touch / click events
    this._prev = element.querySelectorAll('.modal--gallery-navigation-prev')[0];
    this._next = element.querySelectorAll('.modal--gallery-navigation-next')[0];

    for (let i = 0; i < events.length; i++) {
      this.Helpers.on(events[i], this._prev, this.showPrevious);
      this.Helpers.on(events[i], this._next, this.showNext);
    }

    // Setup keyboard events
    this.Helpers.on('keydown', document, this._onKeyPress);

    // Setup swipe events
    this.Helpers.on('touch:swipe-left', element, this.showPrevious);
    this.Helpers.on('touch:swipe-right', element, this.showNext);
  }
Wires the previous / next button to the function to navigation through
the gallery
@param  {Object} element The CSSModal to set up
@return {void}