Couple of little bug fixes for guest users.

apt/create_instance.in

@@ -212,6 +212,10 @@ my $sa_authority = GeniAuthority->Lookup($sa_certificate->urn());
 if (!defined($sa_authority)) {
     fatal("Could not load SA authority object");
 }
+# Guest users default to the APT cluster on the Mothership.
+if ($MAINSITE && !$localuser) {
+    $default_aggregate_urn = $GUEST_URN;
+}
 
 #
 # We use the normal XMLRPC route, so need a context.

www/aptui/status.ajax

@@ -311,7 +311,8 @@ function Do_GetSSHAuthObject()
     }
     
     $nodeid = $ajax_args["nodeid"];
-    $auth   = SSHAuthObject($this_user->uid(), $hostport);
+    $auth   = SSHAuthObject(isset($this_user) ?
+                            $this_user->uid() : $creator->uid(), $hostport);
     if (!$auth) {
 	SPITAJAX_ERROR(1, "Could not create authentication object");
 	return;