Disable maintenance check for API requests

This should be part of the core as the payment one is. There are times when administrators need to update orders while in maintenance mode, and can't if the API is blocked by maintenance mode

upload/catalog/controller/common/maintenance.php

@@ -17,7 +17,7 @@ public function index() {
 
 			$this->user = new User($this->registry);
 
-			if (($route != 'payment') && !$this->user->isLogged()) {
+			if (($route != 'payment' && $route != 'api') && !$this->user->isLogged()) {
 				return new Action('common/maintenance/info');
 			}
 		}
@@ -56,4 +56,4 @@ public function info() {
 			$this->response->setOutput($this->load->view('default/template/common/maintenance.tpl', $data));
 		}
 	}
-}
+}