CIF spanish starting with 'U' bug resolved

[sandeepN06]

Please replace these instructions with a description of your change. The 'New Fields Only' section should be removed if your pull request doesn't add any new fields.

Thanks for your contribution!

Issue : (https://github.com/django/django-localflavor/issues/464)

A checklist is included below which helps us keep the code contributions consistent and helps speed up the review process. You can add additional commits to your pull request if you haven't met all of these points on your first version.

All Changes

• [x] Add an entry to the docs/changelog.rst describing the change.

• [x] Add an entry for your name in the docs/authors.rst file if it's not already there.

New Fields Only

• [ ] Prefix the country code to all fields.

• [ ] Field names should be easily understood by developers from the target localflavor country. This means that English translations are usually not the best name unless it's for something standard like postal code, tax / VAT ID etc.

• [ ] Prefer 'PostalCodeField' for postal codes as it's international English; ZipCode is a term specific to the United States postal system.

• [ ] Add meaningful tests. 100% test coverage is not required but all validation edge cases should be covered.

• [ ] Add .. versionadded:: <next-version> comment markers to new localflavors.

• [ ] Add documentation for all fields.

[sandeepN06]

@benkonrath This is the reference for the change : https://es.wikipedia.org/wiki/C%C3%B3digo_de_identificaci%C3%B3n_fiscal

[benkonrath]

Ok, thanks!