Fix #226 : return on invoices list using reverse url instead of referer

Signed-off-by: CapsLock <faimaison@legeox.net>

coin/billing/admin.py

@@ -12,6 +12,7 @@ from coin.filtering_queryset import LimitedAdminInlineMixin
 from coin.billing.models import Invoice, InvoiceDetail, Payment
 from coin.billing.utils import get_invoice_from_id_or_number
 from coin.offers.models import OfferSubscription
+from django.core.urlresolvers import reverse
 import autocomplete_light
 
 
@@ -155,6 +156,6 @@ class InvoiceAdmin(admin.ModelAdmin):
                 request, 'Vous n\'avez pas l\'autorisation de valider '
                          'une facture.')
 
-        return HttpResponseRedirect(request.META["HTTP_REFERER"])
+        return HttpResponseRedirect(reverse('admin:billing_invoice_changelist'))
 
 admin.site.register(Invoice, InvoiceAdmin)