PT postal codes validation

[istanishev]

Minimal:
Make sure that all short postal codes less than 1000 (short format) are reported as invalid.
The corresponding long format should be 1000 000 - 9999 999.

Nice to have:
According to this https://en.wikipedia.org/wiki/Postal_codes_in_Portugal, it is possible to make the validation even more precise and accept only postal codes for valid regions.