Add crest for executive offices

As agreed the crest will have no identity bar.

https://www.pivotaltracker.com/story/show/42882447
World location news articles are news articles

For public facing things they should apear as news articles. World
location news is an internal name not for the frontend.

Added a view so that the page can have a page title set and a document
type header apear.

https://www.pivotaltracker.com/story/show/46883653
Merge pull request #433 from alphagov/rename-world-news

World location news articles are news articles

https://www.pivotaltracker.com/story/show/46883653
Merge pull request #428 from alphagov/eo-crest

Add crest for executive offices

https://www.pivotaltracker.com/story/show/42882447