Get a list of app users
URL: GET /api/v1/appusers[?name=<appuser_name>]
Content: None
Returns: A list of App Users flitered by appuser_name, if supplied.
Get an app user by ID
URL: GET /api/v1/appusers/<appuser_id>
Content: None
Returns: A single App User whose ID is appuser_id.