Added a python script to get the coefficients value, and a sample model.json value

Thanks for this update, @gptshubham595 . That python script will be useful. Do you think you can:

1. Move the python script to a new folder: lib/scripts so it is outside the Android source tree
2. Write up instructions in a README.md in that same folder, using the info in this page as a starting point: https://altbeacon.github.io/android-beacon-library/distance-calculations2.html

Having instructions will make it easier for other folks to set up the dependencies for the python script, then use it to get new coefficients to be added to the library's config file. Thank you!

Hi,
I've added all the changes! #1115 @davidgyoung,
Do suggest if more changes required! 😀

Reverted back model.json file only added scripts 😊