SEAMVALIDATE-22

extend the helloworld example to demonstrate

1. validation of a method return value
   This commit splits the "name" field into "first name", "middle name" and "last name", adds a composeName method and add a @SiZe validator to its return value ("whole name too long")
2. DI for constraint validators
   Adds a @notbanned validator, checks for "banned names". The list of "banned names" is injected into the validator.

Feel free to scrap this commit or reuse it if you have better ideas how to demonstrate these features in the example...

Cheers!