HV-815 Improving German message for @Length constraint
HV-818 static methods overrides fix
HV-818 Formatting, improving naming, adding method comment
HV-813 Separate @LuhnCheck from @Mod10Check

ModUtil: Separated the Luhn Mod10 variant from mod10Sum method,
corrected methods name convection

- Created @LuhnCheck constraint, LuhnCheckValidator and
LuhnCheckValidatorTest

- Mod10CheckValidator now uses the generic Modulo 10 algorithmn used by
ISBN-13, EAN-8/13/14, GTIN, Identcode and others

- Created Tests for ISBN, EAN and Identcode at Mod10CheckValidator

- AnnotationProcessor updated to include @LuhnCheck

- CreditCardNumber updated to use @LuhnCheck instead @Mod10Check

- Mod Validators code cleanup and Messages update