use our login for admin pages (bug 558510)

apps/zadmin/urls.py

@@ -2,6 +2,7 @@
 from django.contrib import admin
 from django.shortcuts import redirect
 
+from amo.urlresolvers import reverse
 from . import views
 
 
@@ -16,3 +17,12 @@
     # The Django admin.
     url('^models/', include(admin.site.urls)),
 )
+
+
+# Hijack the admin's login to use our pages.
+def login(request):
+    url = '%s?to=%s' % (reverse('users.login'), request.path)
+    return redirect(url)
+
+
+admin.site.login = login