Modify description on organisations of type other

* Modification to describe organisations of type ‘other’ without
reference to the word ‘other’.
* Addition of a helper method to include the organisation’s parental
and child relationships in its description.
* Supporting tests to ensure organisations are described correctly.
Use helper method to describe organisations

Use of the additional helper method to describe the organisation, with
its parental and child relationships.
Refactor helper method

Refactor helper method for description of organisation’s parental and
child relationships
Show unpublishing information on drafts

www.agileplannerapp.com/boards/173808/cards/8902

content designers need to know when a draft is a
fresh draft as opposed to a draft that resulted
from an unpublishing.

this is a temporary fix whilst we create a state
called 'unpublished' to represent such editions.

Add reindex edition by slug endpoint

Story: https://www.pivotaltracker.com/story/show/84836766

This adds an endpoint for triggering a reindex of all documents tagged
to a given slug.

Slugs are only unique across document types, so to insure that a
document with the passed in slug gets reindexed, we select across all
types known to the Document model.

Remove unused Document.document_types method