Add specific errors.
Merge pull request #27 from miloshadzic/exceptions

Add specific errors.
Version 1.2
Update Readme with version note
Update version link
Update gem infrastructure
Update tests to use Minitest
Add and update Changelog
Update countries yaml location (pepe)
Update Changelog
Update README (trliner)
Update version 1.2 link in README
Update Changelog for version 1.2.1
Prefer double quotes
Clean up whitespace
Update changelog for 1.2.2
Fix validating section heading in README
Cleanup whitespace
Memoize country code regexp (tiegz)
Update changelog