Revert "Catch errors raised by edition service observers"

Rescuing StandardError is bad form and can mask all sorts of weird and
wonderful issues. In this instance, one failing listener will result
in all subsequent listeners silently failing to fire.

This reverts commit f67c5bdce83a428d5fd12ac94b1ae6cb2f6becbb.
Rescue exceptions during scheduled publishing

Another temporary fix to ensure that scheduled publishing does not
fail. We rescue exceptions raised by listeners but make sure to log
them with our exception logging in production. Exceptions are still
raised in non-production environments so stuff doesn't accidentally
fall through the cracks.

This is still far from ideal because a listener failing with an
exception will result in all subsequent listeners failing to be
notified. We should do two things:

1. Replace the existing fanout notifier with one that will gracefully
handle individual listeners falling over.
2 Update listeners to handle their own common errors better.
Stub panopticon calls to get build green again

Now we are no longer swallowing notification exceptions, we have
broken tests. This stubs out panopticon registration calls where they
are being made in unit/functional tests and globally in the cucumber
scenarios.
Merge pull request #1310 from alphagov/dont-rescue-all

Don't rescue all exceptions in edition services