Fix current_user 405 error (#312)

[YusufBerki]

What does this PR do?

It fixes the "405 Method Not Allowed" error caused by sending a request to the current_user endpoint with the POST method. The current_user endpoint only supports the GET method.

Why was this PR needed?

The current_user endpoint is currently unavailable due to the error "405 Method Not Allowed"

What are the relevant issue numbers?

312

Does this PR meet the acceptance criteria?

• [ x ] Passes flake8 (refer to .travis.yml)
• [ x ] Docs are buildable
• [ x ] Branch has no merge conflicts with master
• [ x ] Is covered by a test