v3.1.0

Features

• Set back GB country code to be ISO 3166-1 compliant. UK country code will fallback to GB for backward compatibility @jariz
• Update IE zipcode regex @jariz

Miscellaneous

• Update dev dependencies
• Add code coverage
• Add tests
• Add build NPM script
• Setup Travis CI for PR and remote branches
• Setup CD to publish package on new releases
• Keep only useful files for package (reduce package size)