Server: Authentication API about lynx

[RARM]

I added some documentation for the authentication API to make writing tests easier.

[RARM]

I wrote a module for handling user authentication and requests (so the server would recognize the same user) for the client. I created tests for this module. They should be enough for testing the endpoints and the new module.

Although it is two tests only, they are comprehensive tests.

Note that I didn't use Django tests in this case. I didn't do so because we are using a third-party module. I recommend creating a wrapper and testing for that wrapper. But that may be overkill for this soon-to-due and small project.