Converting otbm2json to Python with to_json and to_otbm example scripts

[brzuck]

Ran into some issues (apparently Node limitation) when trying to handle a huge .json file (2.8gb). I converted the script to Python in order to make the conversion while gaining some performance.

Taking about 80 seconds on my PC to convert a 2.8gb formatted json (or 840mb unformatted) to .otbm