Add a contenttype / id prefix to an image upload path

bootstrap.php

<?php

// Appears in your bootstrap file, before the call to $app->run()
$app['upload'] = $app->extend('upload', function ($handler, $app) {
    if ($app['request']->get('contenttype') == 'pages') {
        if ($app['request']->get('contenttypeslug') && $app['request']->get('id')) {
            $handler->setPrefix("/".$app['request']->get('contenttypeslug')."/".$app['request']->get('id'));
        }
    }
    return $handler;
});