Add airport transfers to global nav bookings drop down

Here it is. Another audacious addition to our beloved Rizzo codebase. New Airport Transfers landing page going live today and this adds it to the bookings dropdown. 

![screen shot 2014-10-22 at 9 46 41 am](https://cloud.githubusercontent.com/assets/3247835/4738057/4aa1c258-59fa-11e4-82ac-2a322e5653ab.png)