Try to detect pluralizations when exporting a locale csv file

If a key from the yml file of the source looks like it only contains pluralization keys, instead of exporting those keys we replace them with the pluralization keys from I18n.t('i18n.plural.keys') for the target locale.
Translations export rake tasks have a prereq on :environment

The rails i18n gem adds the pluralization data for the locales, and this doesn't happen if we don't invoke the environment to set things up.  There's also no easy way to do it manually as it's all inside a railtie.
Regen all locales to include proper pluralization forms
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
Merge pull request #315 from alphagov/export_pluralization_forms

https://www.pivotaltracker.com/story/show/45608311