Make the Romanian (ro) phone number field also accept national short numbers

At the moment, the Phone Number field for the "ro" local flavor accepts only the 10 digit regular (geographical or mobile) phone numbers.

This patch allows it to accept national short numbers (3 or 6 digits), which start with the digit "1", and regional or mobile numbers (7 or 10 digits), which start with the digit "0".
Could you add a `versionchanged` here, with a brief summary of the format change? See dc148426a5bbcbc0f1690190a6f595ce3aae6bc6 for an example.