This class estimates the distance between the mobile device and a BLE beacon based on the measured
RSSI and a txPower calibration value that represents the expected RSSI for an iPhone 5 receiving
the signal when it is 1 meter away.
This class uses a best-fit curve equation with configurable coefficients. The coefficients must
be supplied by the caller and are specific to the Android device being used. See the
ModelSpecificDistanceCalculator for more information on the coefficients.
Created by dyoung on 8/28/14.