Added wiring-pi as native gpio in/out capability 

I have added the wiring-pi as an option to utilize, which is more efficient than using the exec call. I have had extreme difficulty with keeping the Pi stable for any longer than a day when I have a continuous sensor hooked up to it, like a Motion Sensor. It took me a while, but I finally found the issue and it was related to the /bin/gpio call. It eventually throws a stack and kernel panic. By replacing this with the actual node-gyp binding-based wiring-pi library, I have been able to sustain the Pi for almost a week and haven't experience any high CPU utilization numbers, either. 

I added "use wiring pi?" as a checkbox to the Node in order to make it a "trial" feature for others to try. We can always remove it later once it seems to be the right choice.