Limited celery concurrency to 1, disabled mingle & gossip

Author: wes-otf

Procfile

@@ -1,3 +1,3 @@
 release: python manage.py migrate --noinput && python manage.py clear_cache --cache=default && python manage.py sync_roles
 web: python manage.py install_languages fr_en ar_en es_en --noinput && gunicorn hypha.wsgi:application --log-file -
-worker: celery --app=hypha.celery worker --autoscale=6,2 --events
+worker: celery --app=hypha.celery worker --concurrency=1 --events --without-gossip --without-mingle