Ticket #263: Added EXECUTE permission to connection permission enum.

extensions/guacamole-auth-mysql/schema/001-create-schema.sql

@@ -112,6 +112,7 @@ CREATE TABLE `guacamole_connection_group_permission` (
   `user_id`             int(11) NOT NULL,
   `connection_group_id` int(11) NOT NULL,
   `permission`          enum('READ',
+                             'EXECUTE',
                              'UPDATE',
                              'DELETE',
                              'ADMINISTER') NOT NULL,