Add python backend example

[dantimofte]

No description provided.

[fidemin]

Dear @dantimofte ,
Thank you for your commit. The correction and addition to server side code with various language was already planned. Now, I only added golang sample code. In regards to pull request about python code you sent, the content of the code is a little bit different what we have expected.
Could you refer to the code for golang? The sample uses not client secret file but client id and client secret directly. Because client secret file is not adaptable for some services of google, the way in sample code is more flexible. Could you please make python directory and add python sample file which is same as the golang code? In README.md file, what you have to do is to add link for python code.

[guruahn]

@dantimofte You have not responded for a long time and close it. Please do a pull request anytime.