Added PiR and MQ-2 to the Arduino

Last night we did some more component testing.  First up, testing the DS18B20 with 20' of Cat-5 cable to see if remote communications would be a problem.  Sensor "Tom" performed flawlessly.  After that I connected up the MQ-2 and watched it stabilize after a couple of minutes of heating.  I do wonder how much current draw it has.  Finally we experimented with a passive IR motion sensor and it was able to spot us moving 20' away!