Add up/down arrow key codes for iOS

I was trying to run through the nodeschool apps using an iOS terminal emulator (ex: Cathode) connected to a host running node and noticed that the up/down arrow keys didn't work in the menu.  I used the code from this module to write a throwaway echo program and observed that iOS was producing x.79.y instead of x.91.y.  I've verified this in a couple different emulator apps, so I'm assuming this is an iOS thing and not a quirk of the emulator.  I haven't been able to find a reference that would make this more authoritative, but here's a PR based on what I can observe.  (iOS7 on an iPad mini)