Add an authors file

[yasoob]

I don't know whether you will accept this or not. Why not make an authors file which will include the name of every contributor ? I know there is pull request history but by adding an Authors file every name is listed in one place.

[JensRantil]

I like this idea, too. The authors could also be listed on the Python Guide website.

[sigmavirus24]

👍 from me too.

[sigmavirus24]

This was accomplished by https://github.com/kennethreitz/python-guide/pull/366