v3 API login changes

In v3, the /login request body field names have been updated.

v2v3
Sign in with POST /v2/Login.json.Sign in with POST /v3/login.

In the request body, the field names have been updated. The response is not in a response_data object.

See /v3/login in the API reference for more information.
Sign out with POST /v2/Logout.json.Sign out with POST /v3/logout.

The response is simply a 200 without any response fields.