Return `200` for all logout requests

This commit should address #33 (/logout never needs to return 401). I'm still kinda new to Javascript, but I'd really like to be able to contribute to this project. If any changes need to be made to this PR, please let me know!

As an aside - should the requests be returning 201 or 200? 201 indicates that a new resource has been created while 200 just indicates success.