2.0.0

• Added asynchronous validation registerAsync() and pass callbacks to passes(func) and fails(func).
• Added array, between, and required_if validation rules.
• Removed Validator.make(..) use new Validator(..) instead.
• Fixed integer rule not allowing unsigned integers.
• Fixed attempting to validate non-required rules when there's nothing to validate.
• Fixed numeric comparison rules where value is a string: size, min, max.
• Fixed error messages for attributes with names: 'has', 'get', or 'first'.
• Errors must now be accessed by .errors.get('username') or .errors.first('username') rather than .errors.username.
• Only validate when calling passes() or fails() (should now be called first before accessing .errors or .errorCount).
• Added ability to format attributes .setAttributeFormatter(function) (by default replaces all _[] with spaces.)
• Added ability to set custom attribute names to display in errors .setAttributeNames().
• Added ability to switch language useLang() and customise/add new languages setMessages().
• Added getMessages(<lang>) to get the raw messages for given language.
• Added getDefaultLang() to return the default language that is being used.
• Use source files in node (no longer uses dist).
• Improved structuring of library, use Browserify, switch to mocha for testing.