Move from the legacy People API to the new one #621
Description
When CPO was written, Google's people API is what allowed us to get an authenticated user's username once we had their token. This API is now deprecated.
CPO is grandfathered in, but any NEW projects created in Google's cloud console don't have access to the API. As a result, pyret.bootstrapworld.org is unable to display the username, and instead falls back to "you are logged in as a guest" even when the user is actually logged in.
We'll need CPO to move to the new API to resolve this.