[FIX] Celery couldn't start without CELERY_APP configured

tools/init.d/gargantext-celery

@@ -24,7 +24,7 @@ CELERYD_PID_FILE=$(grep -oP '^\s*CELERYD_PID_FILE\s*=\s*\K.+' $GARGANTEXT_CONF |
 CELERYD_LOG_FILE=$(grep -oP '^\s*CELERYD_LOG_FILE\s*=\s*\K.+' $GARGANTEXT_CONF | tail -1)
 CELERYD_LOG_LEVEL=$(grep -oP '^\s*CELERYD_LOG_LEVEL\s*=\s*\K.+' $GARGANTEXT_CONF | tail -1)
 
-CELERY_APP=${CELERY_APP:-gargantext}
+CELERY_APP=${CELERY_APP:-gargantext.backend}
 CELERYD_PID_FILE=${CELERYD_PID_FILE:-/tmp/celery.pid}
 CELERYD_LOG_FILE=${CELERYD_LOG_FILE:-celery.log}
 CELERYD_LOG_LEVEL=${CELERYD_LOG_LEVEL:-INFO}