Merge pull request #2133 from edx/feanil/edxapp_worker_signal

Stop celery workers using SIGINT instead of SIGTERM.

playbooks/roles/edxapp/templates/workers.conf.j2

@@ -11,6 +11,7 @@ command={{ edxapp_venv_dir + '/bin/newrelic-admin run-program ' if w.monitor and
 killasgroup=true
 stopasgroup=true
 stopwaitsecs=432000
+stopsignal=INT
 
 {% endfor %}