Cosmetic changes to common_redirect, clientError, serverError

Since these functions exit (or throw exception) after running, there
is no need to have a 'return' statement or similar afterwards.

plugins/FacebookBridge/FacebookBridgePlugin.php

@@ -414,7 +414,6 @@ ENDOFSCRIPT;
                 $action->logout();
 
                 common_redirect($logoutUrl, 303);
-                return false; // probably never get here, but hey
             }
 
             return true;