The easiest way to use libnfc with the Adafruit NFC Breakout is via UART, since it's well-supported by libnfc out of the box. Unfortunately the UART port on the Pi is already dedicated to other purposes, and needs to be freed up for libnfc.
The following steps (based on a clean Raspbian install via noobs) should free UART up for us:
$ sudo raspi-config
Step Two: Disable UART
From the main menu, select option 7 (Serial), then select 'No' to disable shell and kernel messages via UART.
Step Three: Reset
From the command prompt enter the following commands to reboot your Raspberry Pi board, freeing UART up in the process:
$ sudo reboot
