cc2520 pcb documentation
clean up and printf debugging
Merge branch 'master' of github.com:bradjc/raspberrypi-cc2520

Conflicts:
	hardware/eagle/rpi-cc2520/rev_a/rpi-cc2520_a.centroid
	hardware/eagle/rpi-cc2520/rev_a/rpi-cc2520_a.info
	hardware/eagle/rpi-cc2520/rev_a/rpi-cc2520_a.pdf
	hardware/eagle/rpi-cc2520/rev_a/rpi-cc2520_a_pcb.png