Allow other editions to be added to a document series

Designs need updating now that document series have more related
edition types.

Changed the expire_on_next_scheduled_publication to take any related
edition

https://www.pivotaltracker.com/story/show/44367311
Refactor the frontend view

Also changed the styles a bit

For editions with sub types also show the type (speeches, news and
consultations)
Move document_series section to not change designs

Marks suggestion to say: This is part of a series
Merge pull request #262 from alphagov/document-series-associated-to-any-edition

Allow other editions to be added to a document series

https://www.pivotaltracker.com/story/show/44367311