Re-registers unpublished/archived/deleted editions

Editions which have been archived or unpublished in Whitehall don't have
their state updated in Panopticon.

Story: https://www.pivotaltracker.com/story/show/69528904

This adds the "unpublish" and "archive" verbs to the Panopticon
Registrar service listener and sets the adequate state on the
RegisterableEdition object sent to Panopticon.

This solution also requires updating `edition_test#should_remove_published_edition_from_search_index`
since this now triggers an external request.
I'm not entirely sure what this query is meant to be returning. Once an edition is "archived", it's the end of the road, i.e. the user should not be able to re-edition it, so technically there shouldn't be a newer edition of an archived one, nor should it be possible to supersede an archived edition, so this should be an empty set (in reality, there are actually two archived editions that have a newer edition, but I think these are anomalies). 

I \*think\* what you're actually trying to retrieve here are those editions that have been "unpublished" (not archived) and that do not have a later edition that is publicly visible. This is a little tricker to identify as an "unpublished" edition does not get it's own state (it gets reverted back to a draft state) and might get re-published and re-editioned later. I think what you want are all the editions that have an `Unpublishing` associated with them that aren't `UnpublishingReason::Archived` ones and that also don't have a newer edition. You should be able to ignore the actual state of these editions as even if one of the unpublished editions got re-published later, re-registering it as a published edition will have no negative impact.