Add cuke for viewing recently published documents
Rename all_announcements_link to see_all_link
WIP Adding latest#index view

Part of https://www.pivotaltracker.com/story/show/65620588. View currently
only works with an organisation. Topics, Topical Events and World Orgs still to come.
Tidy up cucumber scenario and steps
Fixup scenario
Add #to_s methods to orgs and world locations
Add see all links for all latest document blocks

Includes organisations, world locations, topics and topical events.
Add LatestDocumentsFilter

Exactly matches the way the recently updated documents are generated for
the latest blocks on home pages.
Use LatestDocumentsFilter in LatestController
Add pagination controls to latest page
Use heading in the style of history pages
Decorate the collection of latest documents
Remove unused local from partial