Validator support for Credit Card check

[damyanpetev]

Partially inspired by Data Annotation in MVC, but also seemed reasonable to support such common check.
New option:
creditCard - bool or object with errorMessage, similar to email and other type checks. Inherited.
Description:
Validation is client side and credit card type agnostic - as all of the active issuers can be validated using the Luhn algorithm. Check will match the MVC server side model validation and will be accompanied by a respective option in the Validator Model/Wrapper.