Add enum-style WorldwideOfficeType

It is mandatory for WorldwideOffice (we default all existing rows to the "Other" type).  WorldOfficeTypes can be sorted and grouped as the current set are FCO specific, but we expect other orgs might have their own office types.
Add office type selector to worldwide office admin UI

We default to the Other type rather than forcing a choice for those offices that aren't FCO.  We could maybe remove this default when/if other orgs provide us with their office types.
Add office type to world org api response

not clear if this would be better in the format, or as-is in the details hash.
Strip leading and trailing blank lines in text formatted addresses
Merge pull request #322 from alphagov/worldwide-office-types

https://www.pivotaltracker.com/story/show/45681209