Bump app-validator (bug 830044)

Fix for chained redirects not triggering errors for failed final
status codes.

requirements/prod.txt

@@ -81,7 +81,7 @@ tower==0.3.4
 
 ## Not on pypi.
 -e git://github.com/mozilla/amo-validator.git@e48fbb5830fcb87690d87c5ee9dbaacb78fa9278#egg=amo-validator
--e git://github.com/mozilla/app-validator.git@565d14ef9fb1b18ba33fb3a55f3712097e1c9884#egg=app-validator
+-e git://github.com/mozilla/app-validator.git@0920b5eab41eb7eda92857acc00fc26e13cf3551#egg=app-validator
 -e git://github.com/jsocol/commonware.git@27646ecaca40a89024cc581c3ecf5eb0fa87ee11#egg=commonware
 -e git://github.com/jbalogh/django-queryset-transform@a1ba6ae41bd86f5bb9ff66fb56614e0fafe6e022#egg=django-queryset-transform
 -e git://github.com/miracle2k/django-tables.git@546f339308103880c823b2056830fcdc9220edd0#egg=django-tables