Add postal code validation

[matthewdarwin]

I am using OSMI on a regular basis for address validation. I have a feature request:

Can you please add Postal Code validation for Canada. All postal codes in Canada follow this format: A0A 0A0 or "[A-Z][0-9][A-Z] [0-9][A-Z][0-9]" That is: letter-number-letter-space-number-letter-number, all letters in uppercase.