API gateway versioning

[Tansito]

Summary

This PR includes support in gateway api for different versions and introduce the change in the client.

Details and comments

• Applied versioning structure to support different versions in the API
• Modified the client to start using the versions
• ViewSets to support different versions now has dynamic serializers with get_serializer_class
• Refactorization of ray_job_status_to_model_job_status
• Refactorization of User model inside job to remove the pylint error, now we access the user through get_user_model
• Updated the tests accordingly
• Refactorization of run_program end-point to be just run
• requests package is added to requirements

Fix #308

[akihikokuroda]

LGTM!!

[psschwei]

minor nit: in one place we use if version is None whereas in the other we use version = version or os.environ... do we want to standardize?

[Tansito]

I couldn't standardize them because the use-case is different. In the first scenario I'm receiving a version from the constructor with an standard value but in the second one no, it's a simple function.

My idea is to refactorize save_result inside Job and in that moment I think I'm going to be able to make them equals. But I need to review if I can do that change first and I was trying to avoid to make that in this PR.

Forget it, you are right in fact there was a bug in the logic 😂

[Tansito]

Now it should work as expected @psschwei . If a user specifies a version overrides everything, if not it goes the environment and at the end the default value.

I can't add the version from the user in the second scenario because save_result is outside Job but the logic is similar. My idea is to refactorize that method later in another PR including it in the Job class. I think it has sense but I need to review it well in case there was a reason because we had it like that.

[Tansito]

From what I tested there is no breaking changes in the documentation plus all the changes were internal so merging it right now!