Added least squares polynomial regression code to `sensors.py`.
Implemented `calibrate_dist()` in `sensors.py`.
Merge pull request #18 from aore/master

Merged `ir.readings()` implementation
Revised some comments and removed `_use_calibration_data()`.
Tracking down bugs the logic to get distance readings.
Removed references to calibration from the message protocol.
Fixed some command handlers, and added logic to enqueue
parts of the response message as we go deeper into the
handler functions.
Still tracking down bugs preventing control from getting readings
from rover.
Fixed bugs associated with distance readings and the
`sensors.calibrate_dist()` function.
Merge pull request #13 from dwtj/master

Debugging with calibration