Redirect user to their referer, if the domain is correct.
Redirect user to their referer, if the domain is correct.

Fixes openfoodfacts/openfoodfacts-server#95

openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server