Temporarily enable unpermitted param exceptions

Because we are now using strong params to whitelist filter params on
the document filter pages, I'm temporarily re-enabling the exceptions
raised when unpermitted parameters are posted so that we can ensure
that nothing has slipped through the net.

Assuming all is well on the filter pages, we can disable this again.
I've added a personal reminder for one week's time to remove this
if nothing untoward happens.