Run cron jobs via URL

Kanboard supports running cron jobs via CLI. There are hosting services
that don't offer CLI access, but they do offer calling a URL
periodically. This feature is often used as a CLI cron job replacement.

This commit adds a CronjobController called by "/cronjob" URL that will
execute cron jobs as they were executed via CLI. The URL has public
access, but is protected using the webhook token. The "/cronjob" URL
should be called via HTTPS.

app/ServiceProvider/RouteProvider.php

@@ -180,6 +180,9 @@ class RouteProvider implements ServiceProviderInterface
             // PasswordReset
             $container['route']->addRoute('forgot-password', 'PasswordResetController', 'create');
             $container['route']->addRoute('forgot-password/change/:token', 'PasswordResetController', 'change');
+
+            // Cronjob
+            $container['route']->addRoute('cronjob', 'CronjobController', 'run');
         }
 
         return $container;