added new endpoints
/update_username/v0
/delete_user/v0
/update_password/v0
move data in password related endpoints to request body from params.
/register_username/v0 now takes in app_id as optional parameter to assign user to that app and create session for it.
/generate_access_token/v0 now only needs refresh token (removed validation).
/logout/v0 now only needs refresh token (removed validation).
/update_user_app_ids/v0 now only updates ids for self (user). added access token as input param and removed user_id.
/get_user_app_ids/v0 is now /get_user_details/v0 with access token as the only input param.
**Full Changelog**: https://github.com/thepmsquare/square_authentication/compare/2.0.0...3.0.0