supervisor-xqueue: Allow ora to find its NLTK data (added to environment)

Since the data is not at a standard location anymore, set the location through
a environment variable, `NLTK_DATA`.

playbooks/roles/ora/templates/edx-ora.conf.j2

@@ -16,6 +16,7 @@ env ADDRESS={{ ora_gunicorn_host }}
 env LANG=en_US.UTF-8
 env DJANGO_SETTINGS_MODULE=edx_ora.aws
 env SERVICE_VARIANT=ora
+env NLTK_DATA={{ ora_nltk_data_dir }}
 
 pre-start script
 end script