mod_http_oauth2: Declare additional client registration fields as strings Previously any property not listed in the schema was allowed in any form, which is probably a bit too liberal. Instead, limit extra fields to simple strings, which should still allow localized versions of the various URIs and descriptive properties per RFC 7591 §2.2

local count_registering = module:measure("user_registering", "rate");
local count_registered = module:measure("user_registered", "rate");

module:hook("user-registering", function ()
	count_registering();
end);

module:hook("user-registered", function ()
	count_registered();
end);