Make the bagger menu list scrollable

I did this by setting `max-height` css on `ul.dropdown ul.dropdown` based on window height. The setting is updated when you resize the window. I tested in Chrome on Mac. Please test it in other systems. Here's a live demo:
http://janosgyerik.github.io/BrownBagLunch/baggers.html

Oh I needed to switch to Foundation 4.3.2 (from 4.2.3) because it had a related bug.