Add translations table for Contact
Add translations table for ContactNumber
Use stub_translatable_record in tests

Contact and ContactName are now translatable which was causing the
API::WorldwideOrganisationPresenterTest to fail due to hitting the
database. Using stub_translatable_record and explicitly setting the
contact record for stubbed contact_numbers stops this.
Add admin/contact_translations controller
Make edit contact button text small

The other buttons on the contact listing all have small text so this
just makes them all consistent.
Add translation button for organisation contacts
Add admin/contact_translations_controller#update
Show translations on organisation contacts page
Add edit link to contact translations
Allow contact translations to be deleted
Remove hardcoded paths from contact partial
Contacts only need translations from contactable

If an organisation is translated into Welsh then the associated
contacts only care about Welsh translations.
Make LocalisedModel localise assocations
Clean up #find_contactable in admin controllers
Allow numbers to be translated with contacts
Show RTL contract translations properly in admin
Add support for translating worldwide offices
Clean up contact translation cucumber tests

- Use link text rather than ID
- Be explicit that the organisations need to be translated for contact
  translation to be available
Remove model definitions from migrations

These schema migrations won't be run so far out of step with the code
that the relevant changes aren't present.
Split LocalisedModel#localise_association down