* Add custom message for inclusion validation to include the allowed values.
* Force user to choose document_type from select lik the one shown at verification form.
* Convert stored document_type to a human readable text
We're using `eq` and `match_array` in most places, but there were a few
places where we were still checking each element is included in the
array. This is a bit dangerous, because the array could have duplicate
elements, and we wouldn't detect them with `include`.
* Create admin controller and routes
* Add pagination
* Add search by document_number
* Add EN and ES translations
* Add index specs
* Add missing model specs
