Port all Celery worker functions to discrete pkg

Moves all tasks run by the Celery worker into a discrete package/module
for easier installation. Also adjusts several parameters throughout to
accomplish this.

worker-daemon/pvcworkerd.service

@@ -0,0 +1,20 @@
+# Parallel Virtual Cluster worker daemon unit file
+
+[Unit]
+Description = Parallel Virtual Cluster worker daemon
+After = network.target
+Wants = network-online.target
+PartOf = pvc.target
+
+[Service]
+Type = simple
+WorkingDirectory = /usr/share/pvc
+Environment = PYTHONUNBUFFERED=true
+Environment = PVC_CONFIG_FILE=/etc/pvc/pvc.conf
+ExecStartPre = /bin/sleep 2
+ExecStart = /usr/share/pvc/pvcworkerd.sh
+ExecStopPost = /bin/sleep 2
+Restart = on-failure
+
+[Install]
+WantedBy = pvc.target