fix(celery): set name for celery worker (#585)

Set name for celery worker so that it can be display correct in flower
dashboard.

backend/supervisord.conf

@@ -3,15 +3,15 @@ nodaemon=true
 logfile=/var/log/supervisord.log
 
 [program:celery_worker]
-command=celery -A app.celery worker -Q default --concurrency=5 --loglevel=INFO --logfile=/var/log/celery_worker.log
+command=celery -A app.celery worker -n worker-default@%%h -Q default --concurrency=5 --loglevel=INFO --logfile=/var/log/celery_worker.log
 directory=/app
 stdout_logfile=/var/log/celery_worker_supervisor.log
 stdout_logfile_maxbytes=52428800
 redirect_stderr=true
 autorestart=true
 
 [program:evaluation_worker]
-command=celery -A app.celery worker -Q evaluation --pool=solo --loglevel=INFO --logfile=/var/log/evaluation_worker.log
+command=celery -A app.celery worker -n worker-evaluation@%%h -Q evaluation --pool=solo --loglevel=INFO --logfile=/var/log/evaluation_worker.log
 directory=/app
 stdout_logfile=/var/log/evaluation_worker_supervisor.log
 stdout_logfile_maxbytes=52428800