CIF validation fix
CIF validation fix

CIF Validation failed with cifs ending in 0 and some other. 

I've retrieved it from a pull request on the original repo: https://github.com/lleirborras/ValidateSpanishVAT/pull/1

I've tested this code with some problematic samples and it works OK.

Also, I've added a minor change from an issue on that repository: lleirborras/ValidateSpanishVAT#2
javiertoledo/spanish_vat_validators,leio10/spanish_vat_validators