adding simple validator mock

This class will help people to test their validations

closes #14 
We need to create `new MockValidator` to pass as first parameter and also to pass to `DefaultMessageHelper `. We can't pass the same `Validator to `super` and to `DefaultMessageHelper`.

e.g.
```
//See here, we need to create two different MockValidators
super(new MockValidator(), new DefaultValidationStrategyHelper(new DefaultMessageHelper(new MockValidator(), new MockResult(), new MessageFactory(ResourceBundle.getBundle("messages"))));
```