Closing on mobile, bind touchstart

[kevincobain2000]

Fixes #39

Current bindings are listening to just click events.
https://github.com/kamranahmedse/driver.js/blob/master/src/index.js#L72-L76

  bind() {
    this.window.addEventListener('resize', this.onResize, false);
    this.window.addEventListener('keyup', this.onKeyUp, false);
    this.window.addEventListener('click', this.onClick, false);
  }

I haven't tested it yet, but adding touchstart to bindings should solve the closing problem on mobile devices.

    this.window.addEventListener('touchstart', this.onClick, false);

[kamranahmedse]

thanks