Three tests were also implemented to check initial implementation that now invalidates expired access and refresh tokens and also rotating refresh tokens.
Since I introduced wrapper functions for create_oauth_token to distinguish between access and refresh token there is no need to set the token type in the data dict, since the type is now enforced in the wrapper functions create_access_token and create_refresh_token.
By convention I renamed create_oauth_token to _create_oauth_token as it is considered a private helper function now.
