Improve distance estimation based on device model

[Steppschuh]

Use device model specific factors to compensate for RSSI deltas caused by the phone housing and antenna placement.

[hadiidbouk]

There is a lot of cases here, a device can hold in a landscape mode, or upside down in your pocket.

So checking the antenna placement It will not work here.

[Steppschuh]

Checking for antenna placement is not a suggested solution. It's just a factor that causes deltas. In the end, we will need to measure calibration values for device models that we want to support (e.g. the most commonly used ones). These values will then be used in the distance estimation.

See AltBeacon/android-beacon-library#318, a lot of thoughts have already been made there.