Add first draft admin interface

This exposes information on Services/Sites/Incidents, but does not yet
permit any changes. Admin page also links to future user management
pages.

source/webui/pages/admin.php

@@ -0,0 +1,11 @@
+<?php
+
+$main = StatusBoard_Main::instance();
+$auth = $main->auth();
+
+$services = StatusBoard_Service::all();
+$this->smarty->assign('services', $services);
+
+$users = $auth->listUsers();
+$this->smarty->assign('users', $users);
+?>