Added LCD component interface 
Added GPIO based 4/8 bit LCD display component implementation and
sample program.
Added GPIO based 4/8 bit LCD WiringPi example program
Added StringUtil helper class
Updated serial wiring diagram to correct 5VDC/3VDC power source for
serial port interface.
Merge branch 'develop' of https://github.com/Pi4J/pi4j.git into develop