Added QueueManager to process background jobs

app/Core/Queue/JobHandler.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Kanboard\Core\Queue;
+
+use Kanboard\Core\Base;
+use Kanboard\Job\BaseJob;
+use SimpleQueue\Job;
+
+/**
+ * Class JobHandler
+ *
+ * @package Kanboard\Core\Queue
+ * @author  Frederic Guillot
+ */
+class JobHandler extends Base
+{
+    /**
+     * Serialize a job
+     *
+     * @access public
+     * @param  BaseJob $job
+     * @return Job
+     */
+    public function serializeJob(BaseJob $job)
+    {
+        return new Job(array(
+            'class' => get_class($job),
+            'params' => $job->getJobParams(),
+        ));
+    }
+
+    /**
+     * Execute a job
+     *
+     * @access public
+     * @param Job $job
+     */
+    public function executeJob(Job $job)
+    {
+        $payload = $job->getBody();
+        $className = $payload['class'];
+
+        if (DEBUG) {
+            $this->logger->debug(__METHOD__.' Received job => '.$className);
+        }
+
+        $worker = new $className($this->container);
+        call_user_func_array(array($worker, 'execute'), $payload['params']);
+    }
+}