Create ADXL335Calibration.ino

Calibration Sketch for the ADXL335  
Modified from instructions found https://learn.adafruit.com/adafruit-analog-accelerometer-breakouts/programming to run on the Teensy 3.1 without requiring any additional hardware setup
Uses the Arduino Serial Monitor to trigger calibrations
Runs a calibration each time it receives a "1" from the USB serial 
The calibration should be performed with the accelerometer rotated to min and max positions for each Axis
- calibrations for the same Axis can be repeated
- Results for each calibration are retained through the entire calibration procedure
- Mix/Max Values of 512 indicate that an axis has not been calibrated.