Update prepare() method on Action subclasses.

Fixes handle()-related strict warnings such as "Strict Standards:
Declaration of AdminPanelAction::prepare() should be compatible with
Action::prepare(array $args = Array)

Ref. #190

plugins/OpenID/actions/openidserver.php

@@ -50,7 +50,7 @@ class OpenidserverAction extends Action
 {
     var $oserver;
 
-    function prepare($args)
+    function prepare(array $args = array())
     {
         parent::prepare($args);
         $this->oserver = oid_server();

plugins/OpenID/actions/openidtrust.php

@@ -51,7 +51,7 @@ class OpenidtrustAction extends Action
         return _m('OpenID Identity Verification');
     }
 
-    function prepare($args)
+    function prepare(array $args = array())
     {
         parent::prepare($args);
         common_ensure_session();