Cleanup of validation script. Refactor into template to allow customisation of validation.
Explicitly set error element to 'span' as per new jquery-validate support
[ref: CWPBUG-110]
- Make statics private
- Use Config::get rather than eval to read private statics
- Add a helper function to expose UserDefinedForm_EmailRecipient::$summary_fields
(to make them available for i18n).