Changing maxValue to sensitivity.  Getting the sensitivity from the datasheet
Merge pull request #554 from BrianGenisio/imu-accel-sensitivity

Changing maxValue to sensitivity.  Getting the sensitivity from the datasheet
Merge branch 'master' of github.com:rwaldron/johnny-five into ADXL345

* 'master' of github.com:rwaldron/johnny-five:
  Changing maxValue to sensitivity.  Getting the sensitivity from the datasheet
Updates per review