Add Python3 for running the main.py file

[ndongchrist]

Add python3 main.py as a running method, python main.py is not required for those having python3.

[ndongchrist]

I can work on this Just forked the repo and was unable to run. before realising i had python3.

[catalintabirca]

it depends how the system in set up. you can change the path/alias/ln for python to point to what version you want.

[ndongchrist]

I'm using Linux OS