[#105]: If a tutorial is explicitly closed at any stage, then do not show subsequent steps

The fix has been made in Zurb's code base but not yet incorporated (as of June 2013).
Ref: https://github.com/zurb/joyride/pull/119

I have therefore copied the changes to our local joyride.js file.
Going forward, we could simply upgrade to the new joyride plugin and get the same changes