Extend consumer to support SASL/OAuth

[marcelmarcelD]

• Implemented procedure for getting refresh token
• Implemented procedure for getting access token
• Implemented OAuth2 callback
• Updated requirements.txt file (update version for confluent-kafka library)
• Update version to 1.6.1

[robooo]

Thanks for PR!

I will need first release missing version and after updating to the latest we can look at this one.

Till that time, I would like to leave this as a wrapper without any more functionality, so the token provider + requests_oauthlib and going through the full workflow of oauth is not necessary in this library (+ you can see you hardcoded the parsing of antiforgery but what if someone else doesn't use it or use other naming etc... then it couldn't be re-used and rewriting the TokenProvider would be needed again).
But this could be used as a good example of usage (you can refactor it to examples like test_oauth.robot)

Otherwise the extension of consumer is needed (+ don't forget to extend producer with oauth params too).

[marcelmarcelD]

Hi , thanks for your inputs.

[robooo]

Hi again @marcelmarcelD, so I had a closer look to this implementation and as I said before it will needs more generous approach how to handle the workflow. This is nice example of anti-forgery, cookies, renewal etc. but it would not fit everyone and this library doesn't need to do this stuff (at least I think that). But if you will have some ideas how to make this functionality more generous and optional please don't hesitate and contact me or send PR's!

If you are interested in updating test environment and implementing example how to use oauth please see #21