Api for world office services

Provide new /api/ endpoints for getting a list of world locations and then for a given location get a listing of the organisations that have a presence in that location.

Trying to adhere to the API conventions that are present in alphagov/govuk_content_api ([documented here](https://github.com/alphagov/wiki/wiki/API-conventions)).

In passing we provide more address formatters; we now have text and json on top of the existing hcard formatter.

In a final flourish we redirect from the human readable endpoints to the /api/ endpoints if .json is requested.

Probably want to see what the consumers of this api think of the output (although that'll be easiest once it's on preview).

https://www.pivotaltracker.com/story/show/43754419