Updates to courts table schema

Adds the following fields:
 - uuid
- gov_uk_md5
- details_changed_at
- gov_uk_updated_at

after rake db:migrate, run rake import:uuids to update all court records with uuid.

the validations on lat and long have been removed pending updating all records with UUID, after which they can be re-instated, and the pending test in spec/features/admin/79360856_update_court_with_unrecognised_postcode_spec.rb:31 reinstated.