Add test for well formedness of xml on prod

Also PEP8 fix

Submitting this now so someone else can take a look as I have to take off. It works fine on stage and prod, but for some reason pre-existing tests are failing on dev with this branch, even though nothing that affects those tests has been changed.

Failure: http://qa-selenium.mv.mozilla.com:8080/job/snippets.dev.bob/1/