Added QueueManager to process background jobs

app/Console/WorkerCommand.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Kanboard\Console;
+
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * Class WorkerCommand
+ *
+ * @package Kanboard\Console
+ * @author  Frederic Guillot
+ */
+class WorkerCommand extends BaseCommand
+{
+    protected function configure()
+    {
+        $this
+            ->setName('worker')
+            ->setDescription('Execute queue worker')
+        ;
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $this->queueManager->listen();
+    }
+}