* reran the simple form initializer.
* wrapped submit buttons are now broken and need a fix.
* disabled confirmation validation in client side validations as the
  error message always is attached to the wrong field.

our special error handler for json requests would turn all exceptions
into 500s - removed it. now the rescue_responses can do their thing
again.

enable testing error responses on the full rack stack.

That's the only thing the controller handles meaningful.
Before the route would also catch anything that started with a . interpreting
it as a format string. This lead to lots of false positives in our security
scanner.

Related with https://github.com/pixelated/pixelated-user-agent/issues/924
With @aarni

If you inherit respond to and call it again in your controller
it will not overwrite the previous but add to it.

Since we always have some exceptions from the rules it's probably
easiest to be explicit in the controllers that require it themselves.

for him/herself

So that it we do not expose the is_admin property to anyone else
including other admins.