Merge pull request #2 from stanleyseow/master

Request to merge codes ...
added unused attribute to compatibility to clean compile output

	modified:   librf24-rpi/librf24/compatibility.h
	modified:   librf24-rpi/examples/pingtest.cpp different csn pin
Removed ce() and add spidevice and csn pin to status output
	modified:   librf24-rpi/librf24/RF24.cpp
reordered variables to create a clean compile.
	modified:   librf24-rpi/examples/Makefile
	modified:   librf24-rpi/librf24/RF24.cpp
	modified:   librf24-rpi/librf24/RF24.h